You are under attack! What the hell are you going to do now? Eh?
Stick it out on your own. You and your men are well hard! You can beat Johnny Foreigner single handed. Or die trying. It's Death or Glory!
Be boring and call in air support
Call in tank support. Make it a proper land battle, the way things used to be
Call in the Royal Engineers. For some reason. Maybe they can build something nice and dangerous for you to use