The siege of Corfinium was the first significant military confrontation of Caesar's Civil War. Undertaken in February 49 BCE, it saw the forces of Gaius Julius Caesar's Populares besiege the Italian city of Corfinium, which was held by a force of Optimates under the command of Lucius Domitius Ahenobarbus. The siege lasted only a week, after which the defenders surrendered themselves to Caesar. This bloodless victory was a significant propaganda coup for Caesar and hastened the retreat of the main Optimate force from Italia, leaving the Populares in effective control of the entire peninsula.

Caesar's stay at Corfinium lasted seven days in total and after accepting its surrender he immediately broke camp and set out into Apulia to pursue Pompey. Upon learning of Caesar's victory Pompey began to march his army from Luceria to Canusium and then on to Brundisium where he could further retreat by crossing the Adriatic Sea to Epirus. As he began his march Caesar had with him six legions, having immediately sent Ahenobarbus' legions under Curio to secure Sicily; they would later fight for him in Africa. Pompey would be soon be besieged in Brundisium by Caesar's army, though despite this his evacuation was a success.