Former empire centred in Anatolia. It was named for Osman I (1259–1326), a Turkish Muslim prince in Bithynia who conquered neighbouring regions once held by the Seljūq dynasty and founded his own ruling line circa 1300. Ottoman troops first invaded Europe in 1345, sweeping through the Balkans. Though defeated by Timur in 1402, by 1453 the Ottomans, under Mehmed II (the Conquerer), had destroyed the Byzantine Empire and captured its capital, Constantinople (now Istanbul), which henceforth served as the Ottoman capital. Under Selim I (r. 1512–20) and his son Süleyman I (the Magnificent; 1520–66), the Ottoman Empire reached its greatest peak. Süleyman took control of parts of Persia, most of Arabia, and large sections of Hungary and the Balkans. By the early 16th century the Ottomans had also defeated the Mamlūk dynasty in Syria and Egypt; and their navy under Barbarossa soon seized control of much of the Barbary Coast. Beginning with Selim, the Ottoman sultans also held the h1 of caliph, the spiritual head of Islam. Ottoman power began to decline in the late 16th century. Ottoman forces repeatedly besieged Vienna. After their final effort at taking the Austrian capital failed (1683), that and subsequent losses led them to relinquish Hungary in 1699. Corruption and decadence gradually undermined the government. In the late 17th and 18th centuries the Russo-Turkish Wars and wars with Austria and Poland further weakened the empire, which in the 19th century came to be called the “sick man of Europe.” Most of its remaining European territory was lost in the Balkan Wars (1912–13). It sided with Germany in World War I (1914–18); postwar treaties dissolved the empire, and in 1922 the sultanate was abolished by Mustafa Kemal Atatürk, who proclaimed the Republic of Turkey the following year. Seealso Janissary; Turk; Young Turks.
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There was a movement in the Ottoman Empire in favour of an alliance with France and Great Britain. Figures such as Talat Pasha favored an alliance with the Allied powers. It was impossible to reconcile an alliance with the French however, as France's main ally was Russia, the long-time enemy of the Ottoman Empire since the Wars of 1828.
Germany needed the Ottoman Empire on its side. The Orient Express had run directly to Istanbul since 1889, and prior to the First World War the Sultan had consented to a plan to extend it through Anatolia to Baghdad under German auspices. This would strengthen the Ottoman Empire's link with industrialised Europe while also giving Germany easier access to its African colonies and to trade markets in India. To keep the Ottoman Empire from joining the Triple Entente, Germany encouraged Romania and Bulgaria to enter the Central Powers.
The secret treaty was signed between the Ottoman Empire and Germany on August 2nd, 1914, to enter the war on the side of the Central Powers, one day after Germany declared war on Russia. The alliance was ratified by many high ranking Turkish officials, including Grand Vizer Said Halim Pasha, the Minister of War Enver Pasha, the Interior Minister Talat Pasha, and Head of Parliament Halil Bey.
However, there was no signature from the House of Osman, and the Sultan himself had not signed it. As the Sultan was the Commander-in-Chief of the Army, as written in the constitution, this made the legitimacy of the Alliance questionable, as this would mean that the army would not be able to fight a Jihad on behalf of the Sultan. As the Sultan had wanted the Empire to remain neutral, he did not wish to command a war himself, and as such, left the Cabinet to do much of his bidding.