The Roman Republic had been [[Roman expansion in Italy|aggressively expanding]] in the southern Italian mainland for a century{{sfn|Miles|2011|pp=157–158}} and had conquered peninsular Italy south of the [[Arno River]] by 270{{nbs}}BC, when the Greek cities of southern Italy ([[Magna Graecia]]) submitted.{{sfn|Bagnall|1999|pp=21–22}} During this period of Roman expansion, Carthage, with its capital in what is now [[Tunisia]], had come to dominate southern [[Iberia]], much of the coastal regions of North Africa, the [[Balearic Islands]], [[Corsica]], [[Sardinia]] and the western half of Sicily.{{sfn|Goldsworthy|2006|pp=29–30}} By 264{{nbs}}BC, Carthage was the dominant external power on Sicily, and Carthage and Rome were the preeminent powers in the western Mediterranean.{{sfn|Goldsworthy|2006|pp=25–26}} Relationships were good, the two states had several times declared their mutual friendship and there were strong commercial links.{{sfn|Miles|2011|pp=94, 160, 163, 164–165}}{{sfn|Goldsworthy|2006|pp=69–70}} According to the classicist [[Richard Miles (historian)|Richard Miles]] Rome's expansionary attitude after southern Italy came under its control combined with Carthage's proprietary approach to Sicily caused the two powers to stumble into war more by accident than design.{{sfn|Miles|2011|pp=175–176}} The immediate cause of the [[First Punic War]] was the issue of control of the independent Sicilian [[city state]] of Messana (modern [[Messina]]).{{sfn|Goldsworthy|2006|pp=74–75}} In 264{{nbs}}BC Carthage and Rome went to war.{{sfn|Warmington|1993|p=168}}

The war was fought primarily on Sicily and its surrounding waters; the Romans also unsuccessfully invaded [[North Africa]] in 256{{nbs}}BC.{{sfn|Goldsworthy|2006|p=82}} It was the longest continuous conflict and the greatest naval war of antiquity, with immense materiel and human losses on both sides. In 241{{nbs}}BC, after 23 years of war, the Carthaginians were defeated.{{sfn|Lazenby|1996|p=157}}{{sfn|Bagnall|1999|p=97}} This meant the loss of Carthaginian Sicily to Rome under the terms of the Roman-dictated [[Treaty of Lutatius]].{{sfn|Beck|2015|p=235}} Rome exploited Carthage's distraction during the [[Truceless War]] against rebellious mercenaries and Libyan subjects to break the peace treaty and [[annexation|annex]] Carthaginian [[Sardinia and Corsica]] in 238 BC.{{sfn|Scullard|2006|p=569}}{{sfn|Miles|2011|pp=209, 212–213}} Under the leadership of [[Hamilcar Barca]], Carthage defeated the rebels in 237 BC.{{sfn|Hoyos|2000|p=378}}{{sfn|Hoyos|2007|p=248}}