First clashes (1918)

Ibn Saud himself however did not maintain neutrality through World War I, being generously supported by the British against the pro-Ottoman emirate of Ha'il. In December 1917, a British deputation, led by Colonel Hemilton tried to convince the Saudi leader to take action against the Ha'il emirate of Jabal Shammar. This attempt was unneeded as the Shammar rulers were already hostile and at war with the Saudis since their capture of Riyadh. In return for active campaigning effectively, Ibn Saud demanded firearms, Ibn Saud sought to recapture the Hail under Saudi control like previous Saudi states and get revenge for his father's exile. The British gave him the opportunity. Yet, the British advancement in the Ottoman province of Palestine made the Saudis less relevant, while the Hashemite leader in turn concluded a peace agreement with Jabal Shammar. Thus, in fall of 1918, when Ibn Saud organized some 5,000 men against Jabal Shammar, a British demand to cease military activities came in.

Al-Khurma, a crucial strategic oasis on the way between Nejd and Hejaz, had been under Hashemite rule, but following the dispute between the Saudis and the Hashemites, Khurma's emir Khalid ibn Mansur ibn Luwai defected to the Saudi side.^[2] In July 1918, after the defection of al-Khurma's emir, a detachment was dispatched by Hashemite King to seize al-Khurma. In response, Ibn Saud sent his Ikhwan forces to protect the oasis, defeating the Hashemites from Mecca.

Negotiations

Following the end of World War I, Sharif Husayn sought to strike a deal with Ibn Saud over the al-Khurma oasis. The conflict at that point expanded from a political dispute into a religious sectarian dimension, with the Wahhabis of Nejd standing against the orthodox Sunni Hashemites. Sharif Husayn decided on another expedition to Khurma. Though aware of the coming dispute, the British turned a blind eye to the Hashemite advances, largely underestimating the strength of the Saudis, whom the British thought would be quickly overrun.

Battle of Turaba

In May 1919, a Hashemite army, led by Abdallah ibn Husayn, was dispatched towards Turaba, an oasis some 80 miles away from Khurma. Turaba was seized and plundered on May 21. Ibn Saud dispatched a warning to the Hashemites, that their presence in Turaba or advance on Khurma would provoke a war, but neither side was willing to compromise at that time.

An Ikhwan force, under the command of Sultan bin Bajad, Hamud ibn Umar and Khalid meanwhile advanced on Turaba, and attacked the Hashemites by surprise on May 25–26 in their camp. In a few hours an entire Hashemite army was annihilated, with hundreds killed and thousands escaping in disarray. Abdallah ibn Husayn himself had barely fled the battlefield.

Saudi preparations to conquer Hejaz

The battle of Turaba was a turning point in the conflict, placing Sharif Husayn in a very weak position against Ibn Saud. In early July 1919, Ibn Saud himself arrived to Turaba with an army of 10,000 men, ready to advance on Hejaz. On July 4, however, a British ultimatum arrived to the Saudis, demanding to stop the campaign and return the Nejd. Unwilling to face the British, Ibn Saud submitted to the British demand and capitulated. It however could not change the notion of the Saudi ruler that the victory over Hejaz is possible.