Like this, the enemy would lose access towards the races as well. And I'd also have more time to handle the situation in the other parts of this world.
It was like creating a situation where no one would emerge victorious, or would be able to move a single step forward. This wasn't the most perfect situation for me, for the enemy, but it was still advantageous for me.
Instead of rushing things on all fronts, while losing a lot in doing that, it was best to stabilise one front, and focus on other battlefields.
I wasn't just buying a few days' time for me and my forces, but long weeks and months. That was enough to make me handle the battles on the mainland here, check the new status of the world, and establish the reign of my kingdom here.