Back in the past, you captured soldiers in time? (5)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

A reversal (‘back’) of YMENE, an envelope (‘captured’) of MEN (‘soldiers’) in YE (‘in the past, you’). I have a vague recollection that we have had an inconclusive discussion here about the origin of the idea of the enemy time.