Not sure I've seen míles used for 'corps' (ie. a group of soldiers) like that.
sómá does not seem to be a Latin word. There is a Greek word σῶμα (short a) but it means 'body', not a group of soldiers.
You could always use the plural of míles? Or a word like cohors or legió?
Básílea is not, to my knowledge, a word either, although there was apparently a town called Basiléa (modern Basel). If you want a Latinised form of the Greek βασίλεια 'queen, princess', it would be basilía. I can't think of an actual Latin word for 'Empress'... Augusta seems to be used at Tac. Annals 34, Fronto ad amicós i.14?