The First Punic War did not begin as an inevitable clash between two great powers. Rome and Carthage had affirmed friendship or alliance several times, but the Mamertine seizure of Messana and appeals for help drew both states into the same Sicilian crisis. A Carthaginian presence on the side of Sicily nearest Italy changed Rome's calculation. Ecnomus came in 256 BC, eight years into a twenty-three-year war, so it mattered without deciding the conflict by itself.
Chapter · 26:42-28:45
Sicily turns former partners into First Punic War enemies
Rome and Carthage had repeatedly recognized one another as partners before rival intervention at Messana made control of northeastern Sicily intolerable to Rome.