Longinus was born in Thrace. When he was 25, he joined the Roman army. He served in a Thracian cavalary, where he had the rank of duplicarius – deputy commander of a squad consisting of 32 soldiers. After the end of the service, he probably settled in the veteran colony at Camulodunum.
He was buried in a cemetery by the road from Camulodunum to Londinum. The tombstone is in the museum at the castle in Colchester.