He did it in a delusional thought that he'll be on Griffith's level. GRIFFITH IS A FUCKING GODHAND!
3 chapters! And 2 of them will be of the armies going head to head. The one will be banter of the Emperor and then BOOM, Griffith/Femto/Whoeverdafuck murks his ass!
Onward to Berserk: The Set Fail Arc cont'd