The Battle of Cape Ecnomus or Eknomos was a naval battle, fought off southern Sicily, in 256 BCE, between the fleets of Carthage and the Roman Republic, during the First Punic War (264–241 BCE). The Carthaginian fleet was commanded by Hanno and Hamilcar; the Roman fleet jointly by the consuls for the year, Marcus Atilius Regulus and Lucius Manlius Vulso Longus. It resulted in a clear victory for the Romans. The Roman fleet of 330 warships plus an unknown number of transports had sailed from Ostia, the port of Rome, and had embarked approximately 26,000 picked legionaries shortly before the battle. They planned to cross to Africa and invade the Carthaginian homeland, in what is now Tunisia. The Carthaginians were aware of the Romans' intentions and mustered all available warships, 350, off the south coast of Sicily to intercept them.

With a combined total of about 680 warships carrying up to 290,000 crew and marines, the battle was possibly the largest naval battle in history by the number of combatants involved. When the fleets met, the Carthaginians took the initiative and the battle devolved into three separate conflicts, where the Carthaginians hoped that their superior ship-handling skills would win the day. After a prolonged and confusing day of fighting, the Carthaginians were decisively defeated, losing 30 ships sunk and 64 captured to Roman losses of 24 ships sunk.