I don't get that either. Also not sure where the second letter (E) comes from, assuming that the first is 50 and the 3rd/4th/5th are the soldiers. So I don't get the last 6 letters, or the transport bit.
I'm also stuck on 7d, which no-one else seems to have mentioned, so I must be missing something obvious! Is it like a rainforest or abruptly?? I thought it must be an anagram at first, but I can't find one.