The army of Transjordan (renamed Jordan in 1949) during the first half of the 20th century. It was formed by British authorities in October 1920 after they ousted the Ottoman Turks and seized control of Arab lands. The Legion, which was financed and commanded by British authorities, was a police force tasked with maintaining order in Transjordan and patrolling the road between Jerusalem and Amman. While it was initially made up of 150 fighters, it quickly expanded to 1,000. In 1939, British general John Bagot Glubb, widely known as Glubb Pasha, took command of the Legion and transformed it into the best-trained Arab army. During World War II, the Legion participated on the side of the British forces, and contributed significantly to Allied victories on the Middle East front.
By the 1948 war, the Legion had grown to over 6,000 fighters, 4,500 of whom formed the military contingent that participated in the war. The Legion was originally ordered by the United Nations to withdraw from Palestine back to Transjordan before the British Mandate officially ended in May 1948. But when Zionists announced the establishment of the State of Israel on May 15, the Legion joined other Arab forces and reentered Palestine. Throughout 1948, units of the Legion engaged in several battles with Zionist forces, including the Battle for Jerusalem, retaining the West Bank (including East Jerusalem) by the end of the war. Between 1949 and 1956, the Legion was still commanded by Glubb, but in the wake of sweeping Arab nationalization campaigns across the region, on March 1, 1956, King Hussein relieved Glubb, named his own commander, and ultimately merged the Legion with the Jordanian National Guard—today part of the Jordanian Armed Forces.