Yes, it makes sense when the goal is to cover your own ass. When it doesn't make sense is after you declare total war on the Cagilan Empire in an all or nothing bid to finally break their stranglehold on Atamara, then immediately tie one hand behind your own back by reaffirming a treaty that forces you to march days out of your way to even get to the Cagilan Empire while leaving another major enemy combatant in a virtually unassailable position.
Sorry, bitterness coming through again. Seriously though, the way I look at it is that Darka started a fight that was going to be all or nothing and then chose to voluntarily limit what they could do to win. That is probably the worst way to enter a war that I can think of...
Should have gotten Talerium to join the north. Then no problem.