The Fall of Capua was a battle in 918 between the Carolingian Empire and the League of Napoli, particularly the city-state of Capua. This surprise attack resulted in a Carolingian victory, killing the head of the League of Napoli, Landulf I, along with destroying its capital. It led to the faltering of the Napolitan war effort in the Pentapolis on the Adriatic, the betrayal of the Sicilian Emirate, and the eventual fall of the League of Napoli.
The League of Napoli had become a powerhouse in the two decades of its existence. Expelling the Carolingians from southern Italy and attacking the Pentapolis had seemingly crippled their assets in Italy. Ships from the Sicilian Emirate wreaked havoc on the Carolingian navy in the Adriatic Sea. As the Napolitans fought in the Pentapolis, a large detachment from the western Carolingian fleets began preparations to invade the Napolitan capital of Capua.
On 9 June 918, the Carolingian Navy slipped through Napolitan defenses early in the morning to strike the city of Capua, the capital of the League of Napoli. Following a brief naval battle, Carolingian forces attacked the cities of Naples and Capua. The battle in Naples was relatively easy due to overwhelming Carolingian forces and unpreparedness of the League of Napoli for an invasion of Naples. The battle lasted for roughly a day before Naples was liberated and returned to Carolingian rule.
From Naples, the Carolingians were able to launch an attack on the city of Capua, first attempting to reach the city on 12 June and again the next day. On 16 June, however, a distraction team allowed the Caroligians to attack from the south. Carolingian forces arrived in the morning, attacking the Napolitan city. As the day progressed, the Carolingians entered the city and attacked, setting fire to several portions of the city. While the tide was initially in favor of the Napolitans, the Carolingians were able to turn this around upon the death of Landulf I, the leader of Napoli.
With the loss of their leader, the League of Napoli began to fall apart on the battlefield. By nightfall, Capua belonged to the Carolingian Empire.
The Fall of Capua led to the ascension of Atenulf III as the leader of the League of Napoli. The war effort in the Pentapolis faltered and the Sicilian Emirate began to reassess the wisdom of siding with the League of Napoli. With the loss of Capua as capital of the League of Napoli, Salerno became the new capital until the dissolution of the League of Napoli in 924.