In the reign of Ivan III (r. 1462-1505), the process of gathering in the territories around Moscow was completed. Of the principalities the Ivan III purchased and conquered, the large, rich merchant republic of Novgorod was the most crucial. This prince of Moscow was an autocrat and tsar. This imperious conception of absolute power was powerfully reinforced by two developments. First, about 1480 Ivan III felt strong enough to stop acknowledging the khan as the supreme ruler. Second, after the fall of Constantinople to the Turks in 1453, the tsars saw themselves as the heirs of both the Caesars and Orthodox Christianity, the one true faith. Also, he dispatcheddiplomatic missions to leading Western states.