Rise of the Ottoman Empire
The foundation and rise of the Ottoman Empire is a period of history that started with the emergence of the Ottoman principality in , and ended with the conquest of Constantinople on May 29, 1453. This period witnessed the foundation of a political entity ruled by the Ottoman Dynasty in the northwestern Anatolian region of Bithynia, and its transformation from a small principality on the Byzantine frontier into an empire spanning the Balkans and Anatolia. For this reason, this period in the empire's history has been described as the Proto-Imperial Era. Throughout most of this period, the Ottomans were merely one of many competing states in the region, and relied upon the support of local warlords and vassals to maintain control over their realm. By the middle of the fifteenth century the Ottoman sultans were able to accumulate enough personal power and authority to establish a centralized imperial state, a process which was brought to fruition by Sultan Mehmed II (r. 1451-1481). The conquest of Constantinople in 1453 is seen as the symbolic moment when the emerging Ottoman state shifted from a mere principality into an empire, marking a major turning point in its history.
Ottoman Caliphate
The Turkish national movement, as the details explained in Turkish War of Independence, formed a Turkish Grand National Assembly, and secured formal recognition of the nation's independence and new borders on July 24, 1923 through the Treaty of Lausanne. The National Assembly declared Turkey a republic on October 29, 1923, and proclaimed Ankara its new capital. After over 600 years, the Ottoman Empire had officially ceased to exist. However, under Allied direction, the Sultan pledged to suppress such movements and secured an official fatwa from the Sheikh ul-Islam declaring them to be un-Islamic. But the nationalists steadily gained momentum and began to enjoy widespread support. Many sensed that the nation was ripe for revolution. In an effort to neutralize this threat, the Sultan agreed to hold elections, with the hope of placating and co-opting the nationalists. To his dismay, nationalist groups swept the polls, prompting him to again dissolve parliament in April 1920.