Is it correct to say "Acrchers! Line up!" or there is some other more common command?
I'm not sure how many people these days need to command a group of archers to line up!
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
"Archers! To your positions!" ?
You need to be aware, Marina, that 'dated' language can sound a little odd even when written by native speakers.