Last Stand at Fushimi On Hardest Difficulty Help

This is easily the most difficult mission i've run into in ALL the campaigns.

Any tips?

I've tried going on all in on the right to escort the villies but the castle gets overrun too quickly.

I've tried booming and defending the castle but I get overrun eventually before I can move out to the left.

I've tried a hybrid of pushing right and defending but I can never muster enough forces to make any progress.

I usually age up to try and get flaming arrows, but is it even worth it?

Any advice would be appreciated.

EDIT: This is for DE btw.