Saudi conquest of Hejaz

The Saudi conquest of Hejaz or the Second Saudi-Hashemite War, also known as the Hejaz-Nejd War, was a campaign engaged by Saudi Sultan Abdulaziz to take over the Hashemite Kingdom of Hejaz in 1924–25, ending with conquest and incorporation of Hejaz into the Saudi domain.

Background
The 1924 campaign came within the scope of the historic conflict between the Hashemites of Hejaz and the Saudis of Riyadh (Nejd), which had already sparked the First Saudi-Hashemite War in 1919. The decisive moment that led to the conquest of the Hejaz was the decision in late 1923 by the British government as an economy measure to cease paying subsides to both the feuding families of Arabia, namely the al-Hashemites of the Hejaz and the al-Saud of the Nejd. Without the £60, 000 annual subsidy in gold coins paid to him by the British government, the principle restraint on Ibn Saud was removed. Likewise, the end of the subsides amounting to £25, 000 gold coins per month to Hussein bin Ali al-Hashemite, the Sharif of Mecca, spelled the end of the self-proclaimed "King of the Arabs" as Hussein need British gold coins to bribe Bedouin tribal chiefs to fight for him. During the ensuring campaign of 1924, the Bedouin tribal chiefs of the Hejaz did not rally to the so-called "King of the Arabs" who no longer had the British gold to pay out in bribes, which led to the swift collapse of Hussein's regime.

On 5 March 1924 upon hearing the abolition of the caliphate in Turkey, the Sharif of Mecca proclaimed himself the new caliph and declared that henceforward all Muslims now owed him their unconditional loyalty. The decision of Hussein to proclaim himself caliph sparked massive outrage all over the Muslim world with the overwhelming feeling being that the Sharif had no right to call himself caliph. In Islam, to be awarded the title of caliph requires a consensus by the ulama (clergy) that someone meets the criteria for being caliph. Hussein had made no effort to consult the ulama and proclaimed himself caliph almost on a whim upon hearing that the Ottoman caliphate had just been abolished. On 5 June 1924 at a meeting of the Assembly of Notables in Riyadh, all present urged Ibn Saud to declare jihad on the Sharif for Mecca for his blasphemy in proclaiming himself caliph. Ibn Saud ruled it would be wrong to invade the Hejaz during the pilgrimage season and to wait until the pilgrims to Mecca had finished the haji. In August 1924, Ibn Saud declared jihad on Hussein for his sacrilegious act in proclaiming himself caliph.

Saudi campaign
The pretext for renewed hostilities between Nejd and Hejaz came when the pilgrims from Nejd were denied access to the holy places in Hejaz. On 29 August 1924, Abdulaziz began his military campaign against Hejaz by advancing towards Taif, which surrendered without a major struggle. Following the fall of Taif, the Saudi forces and the allied Ikhwan tribesmen moved on Mecca. Sharif Hussein's request for British assistance was denied to him on the grounds of non-intervention in religious disputes. King Hussein bin Ali had meanwhile fled from Mecca to Jeddah, after the assistance request from his son, King Abdullah of Transjordan was denied as well. The city of Mecca fell without struggle on 13 October 1924. On 16 October 1924, Hussein abdicated as King of the Hejaz and fled the Hejaz, never to return. The Islamic Conference, held in Riyadh on the 29 October 1924, brought a wide Islamic recognition of Ibn-Saud's jurisdiction over Mecca.

By end of October 1924, all the Hashemites held were the port cities of Jeddah and Yanbu along with Medina. The rapid defeat of the Hashemites was due largely to the end of British subsides. Without the bribes in form of British gold that were paid out to the Bedouin chiefs of the Hejaz, the unpopular regime of Hussein promptly collapsed. The merchants of Yanbu, Medina and especially Jeddah were determined not to be conquered by Ibn Saud-whom they viewed as a religious fanatic from the Nejd-and collected their wealth together to fund a makeshift army that allowed Yanbu, Medina and Jeddah to hold out against the al-Saud forces into 1925.

With the advancement of the Saudi forces and blockade imposed on Jeddah, the Hejazi army began to disintegrate. The city of Medina surrendered on 9 December 1925, and Yanbu fell 12 days later. In December 1925 Jeddah was handed to Abdulaziz of Nejd and Saudi forces entering its gates on 8 January 1926, after capitulation and safe passage was negotiated between King bin Ali, Abdulaziz, and the British Consul by the city's ruler Sheikh Abdullah Alireza.

Aftermath
Following the successful takeover over the Kingdom of Hejaz, Abdulaziz was proclaimed King of Hejaz. The Kingdom was later incorporated into the Kingdom of Nejd and Hejaz with Abdulaziz being the king of both in political union.

After stepping down as king, Hussein of Hejaz moved to Aqaba to support his son's war efforts, which made the British force him into exile to Cyprus. Ali bin Hussein, as the King of Hejaz, took office in the middle of a losing war. With the fall of the Kingdom, the dynasty ended up in exile. Hashemites however remained to rule the Emirate of Transjordan and the Kingdom of Iraq.