Stephen succeeded his father on the throne following the latter's death in July 1461 and became the first Bosnian king to receive a crown from the Holy See. The kingdom's existence, however, was increasingly threatened by the Ottomans. King Stephen had the unanimous support of his noblemen in resistance to the Ottomans, but not of the common people. He maintained an active correspondence with Pope Pius II, who forgave him for the loss of Serbia and worked with him to preserve Bosnia for Christendom. The Hungarian king was placated, but all Western monarchs contacted by Stephen refused to assist him. Confident that at least Matthias would come to his aid, Stephen refused to deliver the customary tribute to the Ottoman sultan Mehmed the Conqueror, which provoked an invasion. In May 1463, Mehmed marched into Bosnia, meeting little effective resistance, and captured Stephen, who was then beheaded. The execution marks the fall of the Kingdom of Bosnia to the Ottoman Empire.