Legionary

Suddenly, [...] he saw all this as romantic — the last legionary, his aloneness, the lost cause really lost — and instinctively he pulled in his paunch, stroked down his hair to cover the naked part of the scalp, and wiped the sweat off his cheeks.

a legionary force

1646, Sir Thomas Browne, Pseudodoxia Epidemica (aka, Vulgar Errours), Google Books Unto whom (what is deplorable in men and Christians) too many applying themselves, betwixt jest and earnest, betray the cause of truth, and insensibly make up the legionary body of error.