DeathReaper wrote:For a BT/DE army, it better to think of them not as allies, but as two forces forced to ignore each other to kill the bigger threat on the battlefield...
The same could happen when BT/Tau, or BT/Eldar are on the same battlefield, but are forced to attack the Ork horde coming their way for either of them to have any chance of escape.
Black Templars wouldn't think like that though, they'd just kill everyone until either they'd won or they were dead. I remember reading somewhere where a Black Templar ship was pursuing an Eldar one, then they both came under attack by a much larger Dark Eldar force. Rather than work with the Eldar, they simply got to killing both Eldar and Dark Eldar.