Oops. Forgot I turned that option on in Advanced Set-Up a long time ago.
If you navigate here: C:
\Program Files (x86)\Steam\SteamApps\common\Sid Meier's Civilization V\assets\Gameplay\XML\GameInfo\CIV5GameOptions.xml
inside that file you will find a set of commands:
Code:
<Row>
<Type>GAMEOPTION_ALWAYS_WAR</Type>
<Description>TXT_KEY_GAME_OPTION_ALWAYS_WAR</Description>
<Help>TXT_KEY_GAME_OPTION_ALWAYS_WAR_HELP</Help>
<Visible>0</Visible>
</Row>
if you change the 0 to a 1 in <Visible> like this
Code:
<Row>
<Type>GAMEOPTION_ALWAYS_WAR</Type>
<Description>TXT_KEY_GAME_OPTION_ALWAYS_WAR</Description>
<Help>TXT_KEY_GAME_OPTION_ALWAYS_WAR_HELP</Help>
<Visible>[B][COLOR="Red"]1[/COLOR][/B]</Visible>
</Row>
That will always make the 'Always War' option visible for you to select in Advanced Set-Up. This will be true whether it's a modded game or a non-modded game.
If you know how to make mods you can also make a small mod that has this code in it
Code:
<GameData>
<GameOptions>
<Update>
<Where Type="GAMEOPTION_ALWAYS_WAR" />
<Set Visible="1" />
</Update>
</GameOptions>
</GameData>
Note that where I color-coded blue you might have a slightly different folder path based on what version of windows you have.