Peredur, Peter, Petrinus, Petrion, Petrius
A Roman senator who became a general in the war between Arthur and Lucius Hiberius.
He was present at the first battle, which began after Gawain cut off a Roman warrior’s head during peace negotiations. Gawain and his companions – fearful at how Arthur might react to their actions – concentrated on capturing Petreius Cotta to soothe Arthur’s anger when they returned to him; Boso managed to accomplish this arrest. Without their leader, the Roman brigade fell apart.
Arthur was indeed pleased with his prisoner, he and threw him into a Paris jail. An attempt by the Romans to rescue him failed.
There is a historical record of a Roman senator named Publius Petreius Cotta. He was a member of the Roman Senate during the late Republic period, and he was a contemporary with Julius Caesar. Cotta is known to have served as a legate (a high-ranking military officer) under Caesar during the Gallic Wars, and he played a role in the Roman victory at the Battle of Alesia in 52 BC. After the war, he returned to Rome and resumed his career as a senator.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century
Vulgate Merlin | 1220-1235
Alliterative Morte Arthure | c. 1400