David Drake wrote a book about the Roman legion defeated at Carrhae, postulating that it was sold into slavery to aliens. This roster postulates that they got free and found their way home, just in time to contest the 1879 Martian Punitive Expedition.
The legionaries, with their commanders and clockwork pilia-chuckers:
The cavalry, with their steamtank-busting infernal javelins:
Their light artillery - Sting like a scorpion, float like Buzzy the Hummingbird on Speed:
The giant clockwork dragonfly automaton, for convenient dispensing of naptha under battlefield conditions:
Everything but the dragonfly is by Warlord Games, converted.