During World War I, the British Army underwent a series of campaigns against the Ottoman Empire throughout the Middle East. Though nominally outnumbered by the Ottomans, Britain was able to call upon the aid of two strong allies; the Arabs, which would aid them through irregular warfare in the Ottoman rear, and the Oceanykans, which had pledged to join the Entente in a bid to obtain recognition, protection and open markets from Britain. Furthermore, they received reinforcements from the dominions of India and New Zealand.
British actions began on the 6th of November, 1914, when the Royal Navy shelled the Ottoman fortress of Fao in modern-day Kuwait, initiating the Fao Landing. These forces later received reinforcemenents from the British Raj and the Oceanykan Expeditionary Force, carrying on the Mesopotamian Campaign, in which Ottoman forces were unable to protect Baghdad. Entente forces, by the armistice of 1918, had pushed as far as eastern Turkey despite nightmarish logistics.
Further to the west, on the 1st of February of 1915, Ottoman forces were spotted just across the Suez Canal. This was the first combat test of the Oceanykan Expeditionary Force against an equal, conventional enemy; the result was devastating. Against orders from their British superiors, Oceanykan mounted riflemen went on the assault, inflicting disproportionate losses on the Ottoman troops; these horseback soldiers had been born and raised in the Australian Outback and well-accustomed to desert warfare to an equal or greater degree than the local Berbers and Arabs. After routing all Ottoman forces, the British hurried to build railway-capable crossings across the Suez. While many Oceanykan forces were requisitioned for the bloody and fruitless Gallipoli campaign, 30,000 soldiers (most of them horse, camel and klongen cavalry) remained, and formed the spearpoint of all operations in the region. The 3rd of July, an army of 150,000 crosses the Suez, formally beginning the short-lived Sinai campaign. The Ottomans were reinforced in this front by 20,000 Italian soldiers.
On the border with Libya, an almost purely Oceanykan force of 20,000 mounted rifles began to rampage through the desert in the Maghrebi campaign; the Italian defenders had been cut-off by the French and British fleets, and rarely offered meaningful resistance against the hyperagressive and well-motivated Oceanykan forces. By early 1916, all of Italian Libya had been occupied by the Entente.
29th of August, 1915. The combined Ottoman-German-Italian army is decisively defeated in the Battle of el-Arish. British forces push on, beginning the Palestinian campaign. Within two months, the ANZAC and other British forces at Gallipoli were evacuated; with most of these brought to fight at Palestine. On December 16th, the OEF's tactics of daring horse-and-bayonet charges meet entrenched Ottoman forces with prepared artillery and machinegun positions, securing a phyrric victory in the Battle of Jerusalem. General Fjorn Bickelmore, commander of the OEF, met on numerous occasions with the British high command to discuss the issue of the OEF's replenishment. He argued that traditionally, Oceanykan armies often replenished their manpower in the field by hiring mercenaries, rallying volunteers under an idea, or conscripting locals. An Oceanykan army that was nominally of a few thousand men would end up arriving to the battlefield with twenty or thirty thousand combatants. Thus Oceanykan forces began recruiting or levying local Jews, Arabs, Berbers, Assyrians and Armenians to replenish their numbers; Indians, Coptics and Africans soon joined their ranks from across the Empire. Great Britain paid these soldiers' salaries, and shipped more Oceanykan soldiers from Australia to complement them. Winston Churchill described the practice as "curiously medieval".
As the Russian Empire began breaking and the Entente's balkan allies were thoroughly defeated, fresh Central Powers units were redeployed from the Caucasus, Poland and the Balkans. British forces in Palestine met greater resistance, though they were reinforced by the Oceanykan troops that had successfully taken Libya. The trick up Britain's sleeve were the Arabs, an ethnic group which dominated most of the Ottoman Empire's territory, but which was marginalised. In June of 1916, with promises of British aid and post-war independence, Arab forces assaulted Medina and Mecca, though only the latter was successful. When British reinforcements arrived from Egypt, the Arabian campaign begun.
British forces in Palestine, receiving increasing numbers of local, Oceanykan and Indian reinforcements, went on the offensive once more. On the 5th of January of 1917 the Siege of Damascus begun. By this time Russia was on the edge of collapse and the German Operation Trident had smashed through Entente defensive lines, forcing them to siphon troops from other fronts. Nevertheless, its troops continued fighting on. Despite the constant arrival of fresh Italian, German and Austro-Hungarian units, Entente forces kept slowly pushing, largely thanks to Arab irregulars which wreaked havoc on Ottoman logistics, assisted by Oceanykan nomadic fighters. The Siege of Damascus was won on March of 1918. With unrest brewing throughout the Central Powers, Germany and Austro-Hungary were unable to reinforce their Ottoman allies, whose goverment was collapsing thanks to Armenian, Arab, Greek, Kurdish and Assyrian revolutionary movements. These were all largely sympathetic to the Entente, and fought alongside them. When the armistice was signed on November of 1918, Britain and its allies had just captured the city of Adana, a major port and industrial city in southern Turkey. Instead of surrendering their arms as instructed, Entente forces handed them over to their allied insurrectionists; this influx of state-of-the-art weapons and ammunition was perhaps the final blow to the Ottoman empire.