"useful phrases" from WWII marine training film

There is this interesting grammar in 降参せよ that’s not on bunpro, but supposedly is an imperative form of する. I wonder if it’s still in use anywhere, perhaps it is (was?) suitable in a military setting?

The -よ misuse is quite funny (considering the likely situations), like in 殺さないよ.

Not really sure what you mean entirely, but せよ is on bunpro

It’s listed at the bottom of structures “(2) せよ”