What this song renders
Petillius Cerialis was an experienced Roman officer who would later command the Romano-Batavian war and become consul. In 60 AD he was legate of the Legio IX Hispana, stationed at Lindum (Lincoln) some 90 miles north of Camulodunum. When word reached him of the colonia’s fall, he marched south with a relief vexillation.
Tacitus is brief in Annals 14.32: ‘Petillius Cerialis, legate of the Ninth Legion, hastened to the rescue, but was met by the victorious enemy and his infantry destroyed. Cerialis himself escaped with his cavalry into the fortified camp.’ The infantry losses were enough to take the legion out of operations for the remainder of the revolt.
The engagement is one of the worst single losses by a Roman legion in Britain. Modern estimates put infantry casualties at 1,500–2,000 men. The Ninth was reinforced after the revolt and continued in service, but its reputation took a generation to rebuild — and even later (early second century) it would mysteriously disappear from the historical record.
The ambush, the destruction of the infantry, Cerialis’s escape with the cavalry, and the legion’s removal from the campaign are all in Tacitus. The numbers are modern estimates; the Roman source gives only the structural outcome.