Tempus is the God of War. He is a neutral god that does not take sides in conflict, instead supporting the battle itself rather than the final outcome. This is extended to the directive that his followers must arm their enemy if needed, because a battle with an unarmed enemy would be a slaughter.
Every battle offered must be entered, as cowardice is not allowed. However, mindless warfare without consideration of the consequences is something to be avoided. Tempus does understand that sometimes a battle has no chance of being won, and in these cases he allows retreat as an acceptable alternative.
Warfare should be about strategy and tactics. Therefore, siege warfare should be avoided, as well as total warfare, unless the enemy is vastly superior in all areas and this is the only tactic that will allow one to even enter the battle.
There are other ways to settle conflict besides war, which Tempus does understand, and to a point support. But ultimately be believes those who are not willing to fight for what they believe and hold dear are those whom are bound to lose it.