Osman IV (December 18, 1898 - June 8, 1983) was the Sultan of the Turkish Empire between March 14th, 1923 and May 8th, 1983, thus making his reign over sixty years - the longest reign of any monarch during the 20th century. During his reign, Osman IV was noted for his investment in Turkish infrastructure, his continuation of his father Selim V's attempts to make the Sultanate the secular organ of the state, his expansion of rights in non-Turkish territories of the Empire (in particular the Balkans) and his rebuilding of Turkey as a preeminent world power.
In the latter part of his reign, Osman aligned himself with the Sebastienite-led European Alliance and came to the aid of the EA starting in the fall of 1940 with his invasion of Hungary and later opening of the North African front to distract the Imperial regime from fighting in Germany. When relations with Sebastien soured, it was Osman who aligned instead with the United States during the Black Sea War and despite heavy losses, managed to retake all the Balkan states lost during the 1960's and 70's thanks to the "Unbreakable Friendship" with the United States of America.
Osman also made it a point to normalize relations with the Republic of Arabia and Republic of Syria once they were independent and poured millions into the aid and buffering of Arab states in the region throughout his reign. He backed the Caliphate once it came to power in Arabia during the Islamic Revolution of 1977 despite American protests and famously told President Neill Wallace of the US that, "You can come talk to me before you dictate policy in the Middle East."
Osman IV died on May 8th, 1983 and was succeeded later that day by his eldest son, Osman V.