Caesar's conflict with the Roman Senate had been tearing the Republic apart since he crossed the Rubicon in January 49 BC. After defeating Pompey the Great at the Battle of Pharsalus in Greece and spending a year entangled in Egypt's civil war, Caesar turned his attention to North Africa, where the remaining Optimate forces had concentrated. Their commander was Metellus Scipio, who had assumed leadership after Pompey's assassination. The Optimates had powerful allies: Juba I, King of Numidia, contributed his army and his kingdom's resources to the cause. But Sittius, operating independently in the west, had already invaded the lands of Juba's ally Massinissa II and captured his kingdom. When Juba learned that Sittius was advancing on the Numidian capital of Cirta, the king was forced to turn back from his rendezvous with Scipio to defend his own territory -- a diversion that gave Caesar critical time to prepare for battle.

The Battle of Thapsus was a catastrophe for the Optimates. Despite their numerical superiority, Scipio's army was completely routed by Caesar's forces. The aftermath was savage. Cato the Younger, perhaps the most principled of the Optimate leaders, committed suicide at Utica rather than submit to Caesar. Sittius, meanwhile, captured the retreating commanders Lucius Afranius and Faustus Cornelius Sulla after destroying their cavalry force of a thousand men. These prisoners were either executed at the demands of Caesar's soldiers or killed by mutinous troops in Sittius's own camp -- the sources disagree, but both versions speak to the brutality of the civil war's endgame.

Scipio gathered his remaining supporters and set sail westward with whatever fleet he could muster, hoping to reach safety. But a strong headwind forced the ships to seek port at Hippo Regius on the North African coast. It was here, by sheer chance, that Sittius's mercenary fleet -- now large and well-equipped after months of conquest -- encountered them. The engagement was brief and one-sided. Sittius's larger and more numerous ships surrounded the smaller Optimate vessels. In the battle that followed, every senator aboard perished. Scipio himself took his own life rather than fall into enemy hands. The Optimate cause in Africa died with them.

Caesar rewarded Sittius handsomely. The conquered lands of eastern Numidia were reorganized into the new province of Africa Nova, and Sittius received control of a semi-autonomous region within it called the Confederatio Cirtense. He settled 5,000 legionaries, primarily from Campania, across the cities of Cirta, Milevum, Chullu, and Rusicade. Within two decades, over 20,000 people had migrated from Italy and colonized the area. The settlement became known as Cirta Sittianorum, and the legionaries who controlled it were called Sittiani. It was one of the first serious efforts at Romanization in Africa -- and it began because an exiled conspirator became a freelance warlord, backed the right side almost by accident, and happened to be in the right harbor at the right time.