Cause of the War
The war was caused by several factors, which resulted in a coalition of native Arab families leading revolts against the Ottoman Empire. The Ottomans had just fought World War I and then had to continue with the Third Balkan War, thus weakening their army. Britain offered funding to the rebels in order to ensure a weakened Central Powers and attempt to increase its colonial power following the Great War. This drove the Saudis, Rashidis, Hashemites, and Idrisis, in addition to other powerful families, to unite and gather armies to fight the Ottomans.
The Hashemites and Idrisis were generally in charge of regaining Arab control of the Hejaz. The first battle of the war was a popular revolt, demonstration, and attack against Ottoman rule in Yanbu. While the Hashemites lead a revolt in the Hejaz, the Idrisis fought a revolt in Asir, where they took control of Abha. The fighting continued, and in July, the Hashemites launched an attack on Medina, gaining the city. The Idrisis and Hashemites agreed to meet at Al Bahah. The Idrisis, though, saw issues as their leader died and they lacked unity and a strong military. The British then stopped funding them and instead only funded the Hashemites in the Hejaz. As a result, the Idrisis soon fell out of power in Asir, but retained power until April of 1921. The Hashemites went from Medina south, and began by capturing Jeddah before attacking Mecca. Mecca had been fully fortified and guarded, and the Hashemites required help from the Idrisis, Saudis, British funding, and some Greek Volunteers who favored limiting the power of the Ottoman Empire. In a large show of urban warfare, the Arab rebels were forced out of the city, but they proceeded to besiege it. The siege lasted a month, from late September to the end of October. By the end, however, the Ottomans guarding the city surrendered after severe hunger and some revolts by civilians in the city after the Ottoman troops forced civilians to give up their food to the soldiers. The Masjid al Haram was now controlled by both Hashemites and Saudis, as many of the reinforcements for the Battle of Mecca were loyal to the Saudis. With the Ottoman army in the Hejaz vastly outnumbered, the Saudis and Idrisis sent their troops to conquer the southern part of the Hejaz, while the Hashemites were sent North. By January, all of the Hejaz had been conquered, as had most of the Asir. Furthermore, in January, the Hashemites attacked Tabuk, the final large Ottoman city in the Hejaz and their final large access point to it. However, the Ottomans sent a large force to stop the Hashemite attack, and the Battle of Tabuk was the third largest battle of the war, following only Amman and Mecca, but the Ottomans eventually withdrew. The Hashemites had their army so depleted that they did not advance past Tabuk, and instead held firm. Following the Battle of Tabuk, Asir was secured, and the Hejaz was successfully pried from the Ottomans.
The Rashidis were tasked with conquering land in OTL Jordan and southern Syria. The Ottomans decided to focus on a strategy of waring out the Rashidi army until they would gather a larger army and launch a major assault, catching the Rashdis off guard. The Ottomans were focused on not losing Jordan, Syria or Palestine, and led a series of minor ambushes and some German-funded artillery fire at the Rashidis. However, the Rashidis managed to conquer all of OTL Northern Jordan, in addition to the southern portion of Syria, including Damascus. However, in November of 1920, the Ottoman army gathered and launched a major attack at the Rashidi forces, which had been centered at Amman. The largest battle of the war ensued and the Ottomans won with major casualties on both sides. As a result, the Rashidis left OTL Syria, and instead kept a policy of border patrol similar to that of the Hashmeites, though the Rashidis did successfully fight another Ottoman assault at Qurrayat.