If we remove the 'soldier' part and keep it at 'Romans', probably, but conquering is a definite no.

There problem is interpreting the Roman artifacts we have left behind, as they could either be interpreted as left by Romans or left by people who traded with the Romans, and as Roman Britain is next door, this complicates things. There's quite a number of coins/hoards which are quite problematic, as coins can be shifted all over the place, far from its origin, and a 2nd century coin might be deposited in a 4th century burial, so the provenance of the coins has to be certain. A Roman coin might mean a Roman, but it might also mean an Irish mercenary coming back home. There's Samian ware sherds at Island MacHugh, Roman-style inhumations at Bray Head in County Wicklow, but the former has links to Gaul, and the latter is simply a style - were they Roman, or were they copying the Romans? There's an earlier Roman cremation urn at Stoneyford that might suggest a trading post in the second century and this is our best piece of evidence of Roman presence as it's a fairly particular piece with a particular purpose. There's a gold oculist stamp nearby but were they booty or evidence of a Roman presence is hard to say. There's a distinct possibility that the 'Romans' in some cases were refugees from Scotland/England, or pilgrims from Rome (as there was a sizeable Christian element in Ireland requiring a bishop in the 4th century, which is where Palladius comes in), and traders from mainland Britain.

There are no signs of Roman square encampments in Ireland and no records of them doing so. Agricola, via Tacitus, said that the Romans could take the island with one legion and a few auxiliaries, but while that might indicate an invasion none was undertaken, and Agricola fortified his British coastal defenses against the Irish.