On Blake's side, he was following Alicia's plan and doing the same thing, dividing and conquering. The beastmen who were used to the normal ways of war, where you fought head on, were not used to this kind of tactic that made it impossible to surge forth in numbers.
Alicia had effectively shown that numbers mean nothing in the face of better tactics. Since Alicia was able to split the beastmen off so easily she knew that when it came down to actual war tactics the beast kingdom was way behind.
With every thrust of her sword, Alicia would take another beastman's life or slice down a demonic plague. They had already found multiple whistles on each side allowing for them to have even better control over the battlefield.
They had pushed forward and were now entering the last section. This was where what was left of the beastmen army was located. The original ten thousand that were there had dwindled down a lot, down to a mere three thousand.