In February 1300 a mounted force of Angevin knights and mercenaries under the command of Walter V, Count of Brienne were ordered to secure the surrender of Gagliano. Walter's mounted force was composed of young Angevin-French nobles, many of whom had lost family members in the nearly 20-year long war of the vespers. According to the contemporary Muntaner Chronicle, the nobles referred to themselves as the "Knights of Death" and had vowed vengeance on Sicily for their slain relatives.[2] The total force numbered 300 men of the Knights of Death, complemented with 200 mounted men-at-arms. The Sicilians shadowed the advancing force, setting up watches in the mountainous approaches to Gagliano.[1][3]
When the force arrived a Gagliano, they founded that the castle had not opened its gates. They were quickly confronted by 300 Sicilian knights (likely ethnic Catalans loyal to Frederick)[1] and 300 almogavars, the elite light infantry of Catalonia and Aragon.[1] The Sicilians deployed their infantry in a double-lined 'V' formation in the hills, forcing the Angevins to attack them in disadvantageous terrain. At dawn, the Sicilian infantry sparked their weapons against the rocks before launching waves of deadly throwing spears into the Angevin ranks. The almogavars defied chivalric tradition, ignoring the heavy-armored Angevin knights and instead killing their horses. With the Angevins now disoriented, the Sicilian cavalry charged downhill, routing them. Groups of Angevin knights attempted to hold out on rocky outcroppings, but were gradually captured or killed, with Walter being among the prisoners taken.[1][3]
The battle resulted in the routing and destruction of the Angevin force; few of the horsemen made it back to friendly territory. Sicilian casualties were light. The second major Sicilian victory in the winter of 1299–1300, the battle and its outcome raised Sicilian morale.[1]