The Second Battle of Kosovo (Hungarian: második rigómezei csata, Turkish: İkinci Kosova Muharebesi) was a land battle between a Hungarian-led Crusader army and the Ottoman Empire at Kosovo field that took place from 17–20 October 1448. It was the culmination of a Hungarian offensive to avenge the defeat at Varna four years earlier. In the three-day battle the Ottoman army under the command of Sultan Murad II defeated the Crusader army of regent John Hunyadi. After that battle, the path was clear for the Turks to conquer Serbia and the other Balkan States, it also ended any hopes of saving Constantinople. The Hungarian kingdom no longer had the military and financial resources to mount an offensive against the Ottomans. With the end of the half-century-long Crusader threat to their European frontier, Murad's son Mehmed II was free to lay siege to Constantinople in 1453. Background In 1444, the Hungarian king, Władysław III of Poland, in breach of a ten-year truce that existed with the Ottoman Empire following the Peace of Szeged, launched a new crusade. Meeting the Ottoman forces at the Battle of Varna, the crusading army was destroyed and the king was killed. Two years later in 1446, Sultan Murad II returned to the Balkans seeking revenge for the treaty breaking that preceded the battle. That year his army conquered the Peloponnese then, after the proclamation of a new crusade by Pope Nicholas V, Murad, invaded Albania. Four years after his defeat at Varna, John Hunyadi, the richest landowner in Hungary joined forces with Albania's war leader Gjergj Skanderbeg in an alliance that also included Serbia and Bosnia. Resolved to defeat the Ottoman army Hunyadi raised an army of 24,000 men, including 8,000 Wallachians, his Hungarian cavalry supplemented by German and Bohemian infantry mercenaries. Hunyadi's strategy was based on an expected revolt of the Balkan people, a surprise attack, and the destruction of the main force of the Ottomans in a single battle after linking up with his allies. In September 1448, Hunyadi led his forces across the Danube and camped them in Serbia next to Kovin, just outside the Serbian capital of Smederevo. For a full month the Hungarians stayed encamped awaiting their German, Wallachians, Bohemian and Albanian allies. The Albanian army under Skanderbeg was delayed as it was prevented from linking with Hunyadi's army by the Ottomans and their allies. It is believed that the Albanian army