Ottoman paşa and muşir (field marshal) who became a national hero for his determined resistance at Plevna (modern Pleven (Pleven, Siege of), Bulg.) during the Russo-Turkish War (Russo-Turkish wars) of 1877–78.

After graduation from the military academy of Constantinople, Osman entered the cavalry in 1853 and served in the Crimean War (1853–56). Later, he took part in the campaigns in Lebanon (1860) and Crete (1866–69) and in the suppression of an insurrection in Yemen (1871). He was given command of an army corps at Vidin in 1876, and, following his successes against the Serbian Army, he was promoted to the rank of muşir. During the Russo-Turkish War, after the Russians had crossed the Danube in July 1877, Osman entrenched himself at Plevna on the right flank of the Russian line of communications and maintained his position until December 9, when, compelled to cut his way out, he was wounded and forced to capitulate. This famous defense earned him the title of gazi (“victor in the holy war”), and, after his return from imprisonment in Russia, he was appointed marshal of the sultan's court. Later, Osman served as war minister on four occasions.