The Allies of World War I, Entente Powers, or Allied Powers were a coalition of countries led by France, the United Kingdom, Russia, Italy, Japan, and the United States against the Central Powers of Germany, Austria-Hungary, the Ottoman Empire, Bulgaria, and their colonies during the First World War (19141918).

By the end of the first decade of the 20th century, the major European powers were divided between the Triple Entente and the Triple Alliance. The Triple Entente was made up of France, Britain, and Russia. The Triple Alliance was originally composed of Germany, AustriaHungary, and Italy, but Italy remained neutral in 1914. As the war progressed, each coalition added new members. Japan joined the Entente in 1914 and after proclaiming its neutrality at the beginning of the war, Italy also joined the Entente in 1915. The term "Allies" became more widely used than "Entente", although the Principal Allies of France, Britain, Russia, Italy, and Japan were sometimes known also as Quintuple Entente. The colonies administered by the countries that fought for the allies were also part of the Entente Powers such as British India, French Indochina, and Japanese Korea.

The United States joined near the end of the war in 1917 (the same year in which Russia withdrew from the conflict) as an "associated power" rather than an official ally. Other "associated members" included Serbia, Belgium, Montenegro, Asir, Nejd and Hasa, Portugal, Romania, Hejaz, Panama, Cuba, Greece, China, Siam (now Thailand), Brazil, Armenia, Luxembourg, Guatemala, Nicaragua, Costa Rica, Haiti, Liberia, Bolivia, Ecuador, Uruguay, and Honduras. The treaties signed at the Paris Peace Conference recognised Great Britain, France, Italy, Japan and the United States as 'the Principal Allied and Associated Powers'.

The Battle of Magdhaba took place on 23 December 1916 during the Defence of Egypt section of the Sinai and Palestine Campaign in the First World War. The attack by the Anzac Mounted Division took place against an entrenched Ottoman Army garrison to the south and east of Bir Lahfan in the Sinai desert, some 18–25 miles (29–40 km) inland from the Mediterranean coast. This Egyptian Expeditionary Force (EEF) victory against the Ottoman Empire garrison also secured the town of El Arish after the Ottoman garrison withdrew.

In August 1916, a combined Ottoman and German Empire army had been forced to retreat to Bir el Abd, after the British victory in the Battle of Romani. During the following three months the defeated force retired further eastwards to El Arish, while the captured territory stretching from the Suez Canal was consolidated and garrisoned by the EEF. Patrols and reconnaissances were carried out by British forces, to protect the continuing construction of the railway and water pipeline and to deny passage across the Sinai desert to the Ottoman forces by destroying water cisterns and wells.

By December 1916, construction of the infrastructure and supply lines had sufficiently progressed to enable the British advance to recommence, during the evening of 20 December. By the following morning a mounted force had reached El Arish to find it abandoned. An Ottoman Army garrison in a strong defensive position was located at Magdhaba, some 18–30 miles (29–48 km) inland to the south east, on the Wadi el Arish. After a second night march by the Anzac Mounted Division (Australian and New Zealand Mounted Division), the attack on Magdhaba was launched by Australian, British and New Zealand troops against well-entrenched Ottoman forces defending a series of six redoubts. During the day's fierce fighting, the mounted infantry tactics of riding as close to the front line as possible and then dismounting to make their attack with the bayonet supported by artillery and machine guns prevailed, assisted by aircraft reconnaissances. All of the well-camouflaged redoubts were eventually located and captured and the Ottoman defenders surrendered in the late afternoon.