I'm completely stumped. Why is my morale 0?

https://preview.redd.it/t2og4ggrlebh1.png?width=1205&format=png&auto=webp&s=56f60667a8342f0c672a02c1ea4508f42b8b55fe

I just had a big battle, we won, 1500 vs 1000. Now my morale is suddenly 0, with -87 from "recent events". My party and the castle garrison are full of deserters. Why?