--- a/browser/components/preferences/connection.xul
+++ b/browser/components/preferences/connection.xul
@@ -1,163 +1,152 @@
 <?xml version="1.0"?>
 
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 
-<!DOCTYPE dialog [
-  <!ENTITY % preferencesDTD SYSTEM "chrome://global/locale/preferences.dtd">
-  %preferencesDTD;
-  <!ENTITY % connectionDTD SYSTEM "chrome://browser/locale/preferences/connection.dtd">
-  %connectionDTD;
-  <!ENTITY % mainDTD SYSTEM "chrome://browser/locale/preferences/main.dtd">
-  %mainDTD;
-]>
-
 <?xml-stylesheet href="chrome://global/skin/"?>
 <?xml-stylesheet href="chrome://browser/skin/preferences/preferences.css"?>
 
 <dialog id="ConnectionsDialog" type="child" class="prefwindow"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        title="&connectionsDialog.title;"
+        data-l10n-id="connection-window"
+        data-l10n-attrs="title, style"
         buttons="accept,cancel,help"
         persist="lastSelected screenX screenY"
         role="dialog"
         onbeforeaccept="return gConnectionsDialog.beforeAccept();"
         onload="gConnectionsDialog.checkForSystemProxy();"
         helpTopic="prefs-connection-settings"
-        ondialoghelp="openPrefsHelp()"
+        ondialoghelp="openPrefsHelp()">
 
-#ifdef XP_MACOSX
-        style="width: &window.macWidth2; !important;">
-#else
-        style="width: &window.width2; !important;">
-#endif
+  <link rel="localization" href="browser/preferences/connection.ftl"/>
+  <script type="application/javascript" src="chrome://global/content/l10n.js"></script>
 
   <script type="application/javascript" src="chrome://browser/content/utilityOverlay.js"/>
   <script type="application/javascript" src="chrome://global/content/preferencesBindings.js"/>
   <script type="application/javascript" src="chrome://browser/content/preferences/in-content/extensionControlled.js"/>
 
   <keyset>
-    <key key="&windowClose.key;" modifiers="accel" oncommand="Preferences.close(event)"/>
+    <key data-l10n-id="connection-close-key" modifiers="accel" oncommand="Preferences.close(event)"/>
   </keyset>
 
   <vbox id="ConnectionsDialogPane" class="prefpane largeDialogContainer">
 
     <stringbundle id="bundlePreferences" src="chrome://browser/locale/preferences/preferences.properties"/>
     <stringbundle id="bundleBrand" src="chrome://branding/locale/brand.properties"/>
     <script type="application/javascript" src="chrome://browser/content/preferences/connection.js"/>
 
     <hbox id="proxyExtensionContent" align="top" hidden="true">
       <description control="disableProxyExtension" flex="1" />
       <button id="disableProxyExtension"
               class="extension-controlled-button accessory-button"
-              label="&disableExtension.label;" />
+              data-l10n-id="connection-disable-extension" />
     </hbox>
 
     <groupbox>
-      <caption><label>&proxyTitle.label2;</label></caption>
+      <caption><label data-l10n-id="connection-proxy-configure" /></caption>
 
       <radiogroup id="networkProxyType" preference="network.proxy.type"
                   onsyncfrompreference="return gConnectionsDialog.readProxyType();">
-        <radio value="0" label="&noProxyTypeRadio.label;" accesskey="&noProxyTypeRadio.accesskey;"/>
-        <radio value="4" label="&WPADTypeRadio.label;" accesskey="&WPADTypeRadio.accesskey;"/>
-        <radio value="5" label="&systemTypeRadio.label;" accesskey="&systemTypeRadio.accesskey;" id="systemPref" hidden="true"/>
-        <radio value="1" label="&manualTypeRadio2.label;" accesskey="&manualTypeRadio2.accesskey;"/>
+        <radio value="0" data-l10n-id="connection-proxy-option-no" />
+        <radio value="4" data-l10n-id="connection-proxy-option-system" />
+        <radio value="5" data-l10n-id="connection-proxy-option-auto" id="systemPref" hidden="true" />
+        <radio value="1" data-l10n-id="connection-proxy-option-manual"/>
         <grid class="indent" flex="1">
           <columns>
             <column/>
             <column flex="1"/>
           </columns>
           <rows>
             <row align="center">
               <hbox pack="end">
-                <label accesskey="&http2.accesskey;" control="networkProxyHTTP">&http2.label;</label>
+                <label data-l10n-id="connection-proxy-http" control="networkProxyHTTP" />
               </hbox>
               <hbox align="center">
                 <textbox id="networkProxyHTTP" flex="1"
                          preference="network.proxy.http" onsyncfrompreference="return gConnectionsDialog.readHTTPProxyServer();"/>
-                <label accesskey="&HTTPport.accesskey;" control="networkProxyHTTP_Port">&port2.label;</label>
+                <label data-l10n-id="connection-proxy-http-port" control="networkProxyHTTP_Port" />
                 <textbox id="networkProxyHTTP_Port" class="proxy-port-input" type="number" max="65535" hidespinbuttons="true"
                          preference="network.proxy.http_port" onsyncfrompreference="return gConnectionsDialog.readHTTPProxyPort();"/>
               </hbox>
             </row>
             <row>
               <hbox/>
               <hbox>
-                <checkbox id="shareAllProxies" label="&shareproxy.label;" accesskey="&shareproxy.accesskey;"
+                <checkbox id="shareAllProxies" data-l10n-id="connection-proxy-http-share"
                           preference="network.proxy.share_proxy_settings"
                           onsyncfrompreference="return gConnectionsDialog.updateProtocolPrefs();"/>
               </hbox>
             </row>
             <row align="center">
               <hbox pack="end">
-                <label accesskey="&ssl2.accesskey;" control="networkProxySSL">&ssl2.label;</label>
+                <label data-l10n-id="connection-proxy-ssl" control="networkProxySSL"/>
               </hbox>
               <hbox align="center">
                 <textbox id="networkProxySSL" flex="1" preference="network.proxy.ssl"
                          onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('ssl', false);"/>
-                <label accesskey="&SSLport.accesskey;" control="networkProxySSL_Port">&port2.label;</label>
+                <label data-l10n-id="connection-proxy-ssl-port" control="networkProxySSL_Port" />
                 <textbox id="networkProxySSL_Port" class="proxy-port-input" type="number" max="65535" size="5" preference="network.proxy.ssl_port"
                          hidespinbuttons="true" onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('ssl', true);"/>
               </hbox>
             </row>
             <row align="center">
               <hbox pack="end">
-                <label accesskey="&ftp2.accesskey;" control="networkProxyFTP">&ftp2.label;</label>
+                <label data-l10n-id="connection-proxy-ftp" control="networkProxyFTP"/>
               </hbox>
               <hbox align="center">
                 <textbox id="networkProxyFTP" flex="1" preference="network.proxy.ftp"
                          onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('ftp', false);"/>
-                <label accesskey="&FTPport.accesskey;" control="networkProxyFTP_Port">&port2.label;</label>
+                <label data-l10n-id="connection-proxy-ftp-port" control="networkProxyFTP_Port"/>
                 <textbox id="networkProxyFTP_Port" class="proxy-port-input" type="number" max="65535" size="5" preference="network.proxy.ftp_port"
                          hidespinbuttons="true" onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('ftp', true);"/>
               </hbox>
             </row>
             <row align="center">
               <hbox pack="end">
-                <label accesskey="&socks2.accesskey;" control="networkProxySOCKS">&socks2.label;</label>
+                <label data-l10n-id="connection-proxy-socks" control="networkProxySOCKS"/>
               </hbox>
               <hbox align="center">
                 <textbox id="networkProxySOCKS" flex="1" preference="network.proxy.socks"
                          onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('socks', false);"/>
-                <label accesskey="&SOCKSport.accesskey;" control="networkProxySOCKS_Port">&port2.label;</label>
+                <label data-l10n-id="connection-proxy-socks-port" control="networkProxySOCKS_Port"/>
                 <textbox id="networkProxySOCKS_Port" class="proxy-port-input" type="number" max="65535" size="5" preference="network.proxy.socks_port"
                          hidespinbuttons="true" onsyncfrompreference="return gConnectionsDialog.readProxyProtocolPref('socks', true);"/>
               </hbox>
             </row>
             <row>
               <spacer/>
               <box pack="start">
               <radiogroup id="networkProxySOCKSVersion" orient="horizontal"
                           preference="network.proxy.socks_version">
-                <radio id="networkProxySOCKSVersion4" value="4" label="&socks4.label;" accesskey="&socks4.accesskey;" />
-                <radio id="networkProxySOCKSVersion5" value="5" label="&socks5.label;" accesskey="&socks5.accesskey;" />
+                <radio id="networkProxySOCKSVersion4" value="4" data-l10n-id="connection-proxy-socks4" />
+                <radio id="networkProxySOCKSVersion5" value="5" data-l10n-id="connection-proxy-socks5" />
               </radiogroup>
               </box>
             </row>
-            <label accesskey="&noproxy2.accesskey;" control="networkProxyNone">&noproxy2.label;</label>
+            <label data-l10n-id="connection-proxy-noproxy" control="networkProxyNone"/>
             <textbox id="networkProxyNone" preference="network.proxy.no_proxies_on" multiline="true" rows="2"/>
-            <label control="networkProxyNone">&noproxyExplain.label;</label>
+            <label control="networkProxyNone" data-l10n-id="connection-proxy-noproxy-desc" />
           </rows>
         </grid>
-        <radio value="2" label="&autoTypeRadio2.label;" accesskey="&autoTypeRadio2.accesskey;"/>
+        <radio value="2" data-l10n-id="connection-proxy-autotype" />
         <hbox class="indent" flex="1" align="center">
           <textbox id="networkProxyAutoconfigURL" flex="1" preference="network.proxy.autoconfig_url"
                    oninput="gConnectionsDialog.updateReloadButton();"/>
           <button id="autoReload" icon="refresh"
-                  label="&reload.label;" accesskey="&reload.accesskey;"
+                  data-l10n-id="connection-proxy-reload"
                   oncommand="gConnectionsDialog.reloadPAC();"
                   preference="pref.advanced.proxies.disable_button.reload"/>
         </hbox>
       </radiogroup>
     </groupbox>
     <separator class="thin"/>
     <checkbox id="autologinProxy"
-              label="&autologinproxy.label;"
-              accesskey="&autologinproxy.accesskey;"
-              preference="signon.autologin.proxy"
-              tooltiptext="&autologinproxy.tooltip;"/>
-    <checkbox id="networkProxySOCKSRemoteDNS"  preference="network.proxy.socks_remote_dns" label="&socksRemoteDNS.label2;" accesskey="&socksRemoteDNS.accesskey;" />
+              data-l10n-id="connection-proxy-autologin"
+              preference="signon.autologin.proxy" />
+    <checkbox id="networkProxySOCKSRemoteDNS"
+              preference="network.proxy.socks_remote_dns"
+              data-l10n-id="connection-proxy-socks-remote-dns" />
     <separator/>
   </vbox>
 </dialog>

--- a/browser/components/preferences/in-content/main.xul
+++ b/browser/components/preferences/in-content/main.xul
@@ -671,30 +671,32 @@
     </hbox>
 
     <!-- Please don't remove the wrapping hbox/vbox/box for these elements. It's used to properly compute the search tooltip position. -->
     <hbox>
       <button id="connectionSettings"
               class="accessory-button"
               icon="network"
               data-l10n-id="network-proxy-connection-settings"
-              searchkeywords="&connectionsDialog.title;
-                              &noProxyTypeRadio.label;
-                              &WPADTypeRadio.label;
-                              &systemTypeRadio.label;
-                              &manualTypeRadio2.label;
-                              &http2.label;
-                              &ssl2.label;
-                              &ftp2.label;
-                              &port2.label;
-                              &socks2.label;
-                              &socks4.label;
-                              &socks5.label;
-                              &noproxy2.label;
-                              &noproxyExplain.label;
-                              &shareproxy.label;
-                              &autoTypeRadio2.label;
-                              &reload.label;
-                              &autologinproxy.label;
-                              &socksRemoteDNS.label2;"/>
+              search-l10n-ids="
+                connection-window.title,
+                connection-proxy-option-no.label,
+                connection-proxy-option-auto.label,
+                connection-proxy-option-system.label,
+                connection-proxy-option-manual.label,
+                connection-proxy-http,
+                connection-proxy-ssl,
+                connection-proxy-ftp,
+                connection-proxy-http-port,
+                connection-proxy-socks,
+                connection-proxy-socks4,
+                connection-proxy-socks5,
+                connection-proxy-noproxy,
+                connection-proxy-noproxy-desc,
+                connection-proxy-http-share.label,
+                connection-proxy-autotype.label,
+                connection-proxy-reload.label,
+                connection-proxy-autologin.label,
+                connection-proxy-socks-remote-dns.label
+            " />
     </hbox>
   </hbox>
 </groupbox>

--- a/browser/components/preferences/in-content/preferences.xul
+++ b/browser/components/preferences/in-content/preferences.xul
@@ -22,44 +22,40 @@
   "chrome://browser/locale/preferences/selectBookmark.dtd">
 <!ENTITY % languagesDTD SYSTEM "chrome://browser/locale/preferences/languages.dtd">
 <!ENTITY % fontDTD SYSTEM "chrome://browser/locale/preferences/fonts.dtd">
 <!ENTITY % permissionsDTD SYSTEM "chrome://browser/locale/preferences/permissions.dtd">
 <!ENTITY % passwordManagerDTD SYSTEM "chrome://passwordmgr/locale/passwordManager.dtd">
 <!ENTITY % historyDTD SYSTEM "chrome://mozapps/locale/update/history.dtd">
 <!ENTITY % certManagerDTD SYSTEM "chrome://pippki/locale/certManager.dtd">
 <!ENTITY % deviceManangerDTD SYSTEM "chrome://pippki/locale/deviceManager.dtd">
-<!ENTITY % connectionDTD SYSTEM "chrome://browser/locale/preferences/connection.dtd">
 <!ENTITY % siteDataSettingsDTD SYSTEM
   "chrome://browser/locale/preferences/siteDataSettings.dtd" >
 <!ENTITY % privacyDTD SYSTEM "chrome://browser/locale/preferences/privacy.dtd">
 <!ENTITY % syncBrandDTD SYSTEM "chrome://browser/locale/syncBrand.dtd">
 <!ENTITY % syncDTD SYSTEM "chrome://browser/locale/preferences/sync.dtd">
 <!ENTITY % sanitizeDTD SYSTEM "chrome://browser/locale/sanitize.dtd">
-<!ENTITY % mainDTD SYSTEM "chrome://browser/locale/preferences/main.dtd">
 <!ENTITY % aboutHomeDTD SYSTEM "chrome://browser/locale/aboutHome.dtd">
 <!ENTITY % contentDTD SYSTEM "chrome://browser/locale/preferences/content.dtd">
 <!ENTITY % aboutDialogDTD SYSTEM "chrome://browser/locale/aboutDialog.dtd" >
 %aboutDialogDTD;
 %brandDTD;
 %selectBookmarkDTD;
 %languagesDTD;
 %fontDTD;
 %permissionsDTD;
 %passwordManagerDTD;
 %historyDTD;
 %certManagerDTD;
 %deviceManangerDTD;
-%connectionDTD;
 %siteDataSettingsDTD;
 %privacyDTD;
 %syncBrandDTD;
 %syncDTD;
 %sanitizeDTD;
-%mainDTD;
 %aboutHomeDTD;
 %contentDTD;
 ]>
 
 #ifdef XP_WIN
 #define USE_WIN_TITLE_STYLE
 #endif
 
@@ -72,16 +68,17 @@
   <link rel="localization" href="branding/brand.ftl"/>
   <link rel="localization" href="browser/branding/sync-brand.ftl"/>
   <link rel="localization" href="browser/preferences/preferences.ftl"/>
 
   <!-- Links below are only used for search-l10n-ids into subdialogs -->
   <link rel="localization" href="browser/preferences/blocklists.ftl"/>
   <link rel="localization" href="browser/preferences/clearSiteData.ftl"/>
   <link rel="localization" href="browser/preferences/colors.ftl"/>
+  <link rel="localization" href="browser/preferences/connection.ftl"/>
 
   <script type="text/javascript" src="chrome://global/content/l10n.js"></script>
 
   <html:link rel="shortcut icon"
               href="chrome://browser/skin/settings.svg"/>
 
   <script type="application/javascript"
           src="chrome://browser/content/utilityOverlay.js"/>

--- a/browser/components/preferences/jar.mn
+++ b/browser/components/preferences/jar.mn
@@ -7,17 +7,17 @@ browser.jar:
     content/browser/preferences/applicationManager.js
     content/browser/preferences/blocklists.xul
     content/browser/preferences/blocklists.js
     content/browser/preferences/clearSiteData.css
     content/browser/preferences/clearSiteData.js
     content/browser/preferences/clearSiteData.xul
 *   content/browser/preferences/colors.xul
     content/browser/preferences/colors.js
-*   content/browser/preferences/connection.xul
+    content/browser/preferences/connection.xul
     content/browser/preferences/connection.js
     content/browser/preferences/fonts.xul
     content/browser/preferences/fonts.js
     content/browser/preferences/handlers.xml
     content/browser/preferences/handlers.css
     content/browser/preferences/languages.xul
     content/browser/preferences/languages.js
     content/browser/preferences/permissions.xul

new file mode 100644
--- /dev/null
+++ b/browser/locales/en-US/browser/preferences/connection.ftl
@@ -0,0 +1,83 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+connection-window =
+    .title = Connection Settings
+    .style =
+        { PLATFORM() ->
+            [macos] width: 44em
+           *[other] width: 49em
+        }
+
+connection-close-key =
+    .key = w
+
+connection-disable-extension =
+    .label = Disable Extension
+
+connection-proxy-configure = Configure Proxy Access to the Internet
+
+connection-proxy-option-no =
+    .label = No proxy
+    .accesskey = y
+connection-proxy-option-system =
+    .label = Use system proxy settings
+    .accesskey = U
+connection-proxy-option-auto =
+    .label = Auto-detect proxy settings for this network
+    .accesskey = w
+connection-proxy-option-manual =
+    .label = Manual proxy configuration
+    .accesskey = M
+
+connection-proxy-http = HTTP Proxy
+    .accesskey = x
+connection-proxy-http-port = Port
+    .accesskey = P
+connection-proxy-http-share =
+    .label = Use this proxy server for all protocols
+    .accesskey = s
+
+connection-proxy-ssl = SSL Proxy
+    .accesskey = L
+connection-proxy-ssl-port = Port
+    .accesskey = o
+
+connection-proxy-ftp = FTP Proxy
+    .accesskey = F
+connection-proxy-ftp-port = Port
+    .accesskey = r
+
+connection-proxy-socks = SOCKS Host
+    .accesskey = C
+connection-proxy-socks-port = Port
+    .accesskey = t
+
+connection-proxy-socks4 =
+    .label = SOCKS v4
+    .accesskey = K
+connection-proxy-socks5 =
+    .label = SOCKS v5
+    .accesskey = v
+connection-proxy-noproxy = No Proxy for
+    .accesskey = N
+
+connection-proxy-noproxy-desc = Example: .mozilla.org, .net.nz, 192.168.1.0/24
+
+connection-proxy-autotype =
+    .label = Automatic proxy configuration URL
+    .accesskey = A
+
+connection-proxy-reload =
+    .label = Reload
+    .accesskey = e
+
+connection-proxy-autologin =
+    .label = Do not prompt for authentication if password is saved
+    .accesskey = i
+    .tooltip = This option silently authenticates you to proxies when you have saved credentials for them. You will be prompted if authentication fails.
+
+connection-proxy-socks-remote-dns =
+    .label = Proxy DNS when using SOCKS v5
+    .accesskey = D

deleted file mode 100644
--- a/browser/locales/en-US/chrome/browser/preferences/connection.dtd
+++ /dev/null
@@ -1,49 +0,0 @@
-<!-- This Source Code Form is subject to the terms of the Mozilla Public
-   - License, v. 2.0. If a copy of the MPL was not distributed with this
-   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-
-
-<!ENTITY  connectionsDialog.title       "Connection Settings">
-<!ENTITY  window.width2                 "49em">
-<!ENTITY  window.macWidth2              "44em">
-
-<!ENTITY  proxyTitle.label2             "Configure Proxy Access to the Internet">
-<!ENTITY  noProxyTypeRadio.label        "No proxy">
-<!ENTITY  noProxyTypeRadio.accesskey    "y">
-<!ENTITY  systemTypeRadio.label         "Use system proxy settings">
-<!ENTITY  systemTypeRadio.accesskey     "u">
-<!ENTITY  WPADTypeRadio.label           "Auto-detect proxy settings for this network">
-<!ENTITY  WPADTypeRadio.accesskey       "w">
-<!ENTITY  manualTypeRadio2.label        "Manual proxy configuration">
-<!ENTITY  manualTypeRadio2.accesskey    "m">
-<!ENTITY  autoTypeRadio2.label          "Automatic proxy configuration URL">
-<!ENTITY  autoTypeRadio2.accesskey      "A">
-<!ENTITY  reload.label                  "Reload">
-<!ENTITY  reload.accesskey              "e">
-<!ENTITY  ftp2.label                    "FTP Proxy">
-<!ENTITY  ftp2.accesskey                "F">
-<!ENTITY  http2.label                   "HTTP Proxy">
-<!ENTITY  http2.accesskey               "x">
-<!ENTITY  ssl2.label                    "SSL Proxy">
-<!ENTITY  ssl2.accesskey                "L">
-<!ENTITY  socks2.label                  "SOCKS Host">
-<!ENTITY  socks2.accesskey              "C">
-<!ENTITY  socks4.label                  "SOCKS v4">
-<!ENTITY  socks4.accesskey              "K">
-<!ENTITY  socks5.label                  "SOCKS v5">
-<!ENTITY  socks5.accesskey              "v">
-<!ENTITY  socksRemoteDNS.label2         "Proxy DNS when using SOCKS v5">
-<!ENTITY  socksRemoteDNS.accesskey      "d">
-<!ENTITY  port2.label                   "Port">
-<!ENTITY  HTTPport.accesskey            "P">
-<!ENTITY  SSLport.accesskey             "o">
-<!ENTITY  FTPport.accesskey             "r">
-<!ENTITY  SOCKSport.accesskey           "t">
-<!ENTITY  noproxy2.label                "No Proxy for">
-<!ENTITY  noproxy2.accesskey            "n">
-<!ENTITY  noproxyExplain.label          "Example: .mozilla.org, .net.nz, 192.168.1.0/24">
-<!ENTITY  shareproxy.label              "Use this proxy server for all protocols">
-<!ENTITY  shareproxy.accesskey          "s">
-<!ENTITY  autologinproxy.label          "Do not prompt for authentication if password is saved">
-<!ENTITY  autologinproxy.accesskey      "i">
-<!ENTITY  autologinproxy.tooltip        "This option silently authenticates you to proxies when you have saved credentials for them. You will be prompted if authentication fails.">

deleted file mode 100644
--- a/browser/locales/en-US/chrome/browser/preferences/main.dtd
+++ /dev/null
@@ -1,1 +0,0 @@
-<!ENTITY disableExtension.label    "Disable Extension">

--- a/browser/locales/jar.mn
+++ b/browser/locales/jar.mn
@@ -51,21 +51,19 @@
     locale/browser/safebrowsing/phishing-afterload-warning-message.dtd (%chrome/browser/safebrowsing/phishing-afterload-warning-message.dtd)
     locale/browser/safebrowsing/report-phishing.dtd                    (%chrome/browser/safebrowsing/report-phishing.dtd)
     locale/browser/safebrowsing/safebrowsing.properties   (%chrome/browser/safebrowsing/safebrowsing.properties)
     locale/browser/feeds/subscribe.dtd              (%chrome/browser/feeds/subscribe.dtd)
     locale/browser/feeds/subscribe.properties       (%chrome/browser/feeds/subscribe.properties)
     locale/browser/migration/migration.dtd         (%chrome/browser/migration/migration.dtd)
     locale/browser/migration/migration.properties  (%chrome/browser/migration/migration.properties)
     locale/browser/preferences/clearSiteData.properties     (%chrome/browser/preferences/clearSiteData.properties)
-    locale/browser/preferences/connection.dtd         (%chrome/browser/preferences/connection.dtd)
     locale/browser/preferences/content.dtd            (%chrome/browser/preferences/content.dtd)
     locale/browser/preferences/fonts.dtd              (%chrome/browser/preferences/fonts.dtd)
     locale/browser/preferences/languages.dtd          (%chrome/browser/preferences/languages.dtd)
-    locale/browser/preferences/main.dtd               (%chrome/browser/preferences/main.dtd)
     locale/browser/preferences/permissions.dtd        (%chrome/browser/preferences/permissions.dtd)
     locale/browser/preferences/preferences.properties     (%chrome/browser/preferences/preferences.properties)
     locale/browser/preferences/privacy.dtd            (%chrome/browser/preferences/privacy.dtd)
     locale/browser/preferences/security.dtd           (%chrome/browser/preferences/security.dtd)
     locale/browser/preferences/selectBookmark.dtd     (%chrome/browser/preferences/selectBookmark.dtd)
     locale/browser/preferences/siteDataSettings.dtd     (%chrome/browser/preferences/siteDataSettings.dtd)
     locale/browser/preferences/sync.dtd               (%chrome/browser/preferences/sync.dtd)
     locale/browser/preferences/translation.dtd        (%chrome/browser/preferences/translation.dtd)

new file mode 100644
--- /dev/null
+++ b/python/l10n/fluent_migrations/bug_1451992_preferences_connection.py
@@ -0,0 +1,467 @@
+# coding=utf8
+
+# Any copyright is dedicated to the Public Domain.
+# http://creativecommons.org/publicdomain/zero/1.0/
+
+from __future__ import absolute_import
+import fluent.syntax.ast as FTL
+from fluent.migrate.helpers import MESSAGE_REFERENCE
+from fluent.migrate import COPY, CONCAT, REPLACE
+
+def migrate(ctx):
+    """Bug 1451992 - Migrate Preferences::Subdialogs::Connection to Fluent, part {index}."""
+
+    ctx.add_transforms(
+        'browser/browser/preferences/connection.ftl',
+        'browser/browser/preferences/connection.ftl',
+        [
+            FTL.Message(
+                id=FTL.Identifier('connection-window'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('title'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'connectionsDialog.title'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('style'),
+                        FTL.Pattern(
+                            elements=[
+                                FTL.Placeable(
+                                    expression=FTL.SelectExpression(
+                                        expression=FTL.CallExpression(
+                                            callee=FTL.Function('PLATFORM')
+                                        ),
+                                        variants=[
+                                            FTL.Variant(
+                                                key=FTL.VariantName('macos'),
+                                                default=False,
+                                                value=CONCAT(
+                                                    FTL.TextElement('width: '),
+                                                    COPY(
+                                                        'browser/chrome/browser/preferences/connection.dtd',
+                                                        'window.macWidth2'
+                                                    )
+                                                )
+                                            ),
+                                            FTL.Variant(
+                                                key=FTL.VariantName('other'),
+                                                default=True,
+                                                value=CONCAT(
+                                                    FTL.TextElement('width: '),
+                                                    COPY(
+                                                        'browser/chrome/browser/preferences/connection.dtd',
+                                                        'window.width2'
+                                                    )
+                                                )
+                                            )
+                                        ]
+                                    )
+                                )
+                            ]
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-close-key'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('key'),
+                        COPY(
+                            'toolkit/chrome/global/preferences.dtd',
+                            'windowClose.key'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-disable-extension'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/main.dtd',
+                            'disableExtension.label'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-configure'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'proxyTitle.label2'
+                )
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-option-no'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'noProxyTypeRadio.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'noProxyTypeRadio.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-option-system'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'systemTypeRadio.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'systemTypeRadio.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-option-auto'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'WPADTypeRadio.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'WPADTypeRadio.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-option-manual'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'manualTypeRadio2.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'manualTypeRadio2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-http'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'http2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'http2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-http-port'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'port2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'HTTPport.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-http-share'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'shareproxy.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'shareproxy.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-ssl'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'ssl2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'ssl2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-ssl-port'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'port2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'SSLport.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-ftp'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'ftp2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'ftp2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-ftp-port'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'port2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'FTPport.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-socks'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'socks2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socks2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-socks-port'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'port2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'SOCKSport.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-socks4'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socks4.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socks4.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-socks5'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socks5.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socks5.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-noproxy'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'noproxy2.label'
+                ),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'noproxy2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-noproxy-desc'),
+                value=COPY(
+                    'browser/chrome/browser/preferences/connection.dtd',
+                    'noproxyExplain.label'
+                )
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-autotype'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'autoTypeRadio2.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'autoTypeRadio2.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-reload'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'reload.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'reload.accesskey'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-autologin'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'autologinproxy.label'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'autologinproxy.accesskey'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('tooltip'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'autologinproxy.tooltip'
+                        )
+                    )
+                ]
+            ),
+            FTL.Message(
+                id=FTL.Identifier('connection-proxy-socks-remote-dns'),
+                attributes=[
+                    FTL.Attribute(
+                        FTL.Identifier('label'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socksRemoteDNS.label2'
+                        )
+                    ),
+                    FTL.Attribute(
+                        FTL.Identifier('accesskey'),
+                        COPY(
+                            'browser/chrome/browser/preferences/connection.dtd',
+                            'socksRemoteDNS.accesskey'
+                        )
+                    )
+                ]
+            )
+        ]
+    )