A lot of things happened at once.
From the depths of Layn's formation, someone blew a horn. Given how small their numbers were, using this kind of loud instrument didn't make any real sense...
Or so could a random officer from either of their opposing armies think.
Because the moment the sound of the horn struck everyone on the battlefield... Slavians' right wing started to give ground.
They didn't run away just like that, but all the fighting between them at the flank commanded by Al... Suddenly died off. Which was peculiar, given how just a few meters further, where Layn's forces ended and the cultivators army began, the fight went on just like before.
In this moment of respite, Al moved with his men sweeping at the center of the Slavian's formation. With the help of the strongest troops, the balance of the fight broke apart, forcing the center of the Slavians into an unorganized retreat.