Second Saudi-Rashidi War (1915–1918)

The Second Saudi-Rashidi War (1915–1918) took place between the British-aligned Emirate of Nejd and Hasa and the Emirate of Jabal Shammar, which was an ally of the Ottoman Empire.

Background
After the First Saudi–Rashidi War, the Emirate of Nejd and Hasa gained control of all the land south of the Qassim region in what is now modern-day Saudi Arabia. At that time, both Nejd and Jabal Shammar were aligned with the Ottoman Empire and acted largely under its direction. In 1913, Nejd took over the territory of Al Hasa from the Ottoman Empire.

Neutrality and alignments during WWI
During the First World War, Nejd remained neutral. Jabal Shammar initially declared neutrality but later provided varying levels of support to the Ottomans. Kuwait declared neutrality but received British protection due to their established relations, supported by treaties such as the Anglo-Kuwaiti Agreement of 1899.

Negotiations
Captain William Shakespear served as a military advisor to Ibn Saud, while the British established contact with the Emirate of Nejd and Hasa. During the First World War, the British sought to ally with the Emirate of Nejd and Hasa to counter Jabal Shammar, whose raids were jeopardizing British operations in the Mesopotamian Campaign. At the same time, the Ottomans were also seeking to form an alliance and began negotiations for cooperation.

The Battle of Jarrab
During the Battle of Jarrab, Ibn Saud's cavalry defeated Al Rashid's cavalry, but Al Rashid's infantry emerged victorious over Ibn Saud's infantry. The Ajman forces betrayed Ibn Saud, which led to the sacking of his camp and sparked the Ajman revolt. Notably, Shakespear died in combat during the battle. His death affected British trust in Ibn Saud, which in turn influenced the course of the Arab Revolt.

The Treaty of Darin
The Treaty of Darin was an agreement between the Emirate of Nejd and Hasa and the United Kingdom. It established a formal territorial boundary for Nejd and Hasa, with the British committing to providing financial assistance and weapons in exchange for Nejd and Hasa agreeing not to engage in hostilities against any of the United Kingdom's allies. The Treaty of Darin served as the impetus for Nejd and Hasa to declare war on Jabal Shammar.

Supplying Ibn Saud and Al Rashid
At the beginning of 1915, the Ottomans provided Jabal Shammar with 10,000 rifles and ammunition, while Nejd received a monthly stipend of £5,000, which was increased during the war. Furthermore, they obtained weapons from the British.

Ajman revolt and early clashes
During much of 1915, Nejd was occupied with suppressing the Ajman revolt that broke out after the Battle of Jarrab. The most significant battle during this conflict was the Battle of Kanzan. The British authorities viewed Ibn Saud's military tactics with skepticism. Therefore, in November 1916, Percy Cox arranged a meeting with Abdulaziz and Jabir Al Sabah in Basra to reconcile the hostility between the Sauds and the Ajman tribe. This diplomatic effort led to an agreement that both parties would refrain from attacking each other. Meanwhile, Ha'il conducted raids against Nejd and Kuwait throughout the year. In early 1916, Kuwait supported Nejd by sending 200 men to assist in its defense.

Jabal Shammar's actions in 1916 and 1917
Jabal Shammar faced resistance from the local population as it struggled against Nejd. In March 1917, Shammar launched a significant attack on Hejaz. They continued raiding along the Hejaz railway, targeting Hejaz forces and providing assistance in the siege of Medina.

The arrival of Percy Cox and Britain's requests for Ibn Saud
Percy Cox replaced William Shakespear as the United Kingdom's liaison to Ibn Saud. He held this position until 1922 when he facilitated the signing of the Treaty of Darin. John Philby was sent by the British to encourage Ibn Saud's participation in the war effort and the start of an offensive. However, the British were unaware that Nejd was already in conflict with the Central Powers. Nejd explained that launching a military offensive at that time was not feasible due to the rugged and mountainous terrain of Jabal Shammar. Additionally, Nejd cited the strong fortifications of Jabal Shammar and their limited arsenal of weapons as further hindrances. In late 1918, at the British request, Nejd acquiesced and initiated an offensive against Jabal Shammar.

Nejd's final 1918 offensive
Nejd's final offensive began on August 5, 1918, with 5,000 troops. By September, they had almost reached Ha'il, but Nejd terminated the offensive in October due to Hejaz making peace with Jabal Shammar. The British advised them to cease as they wished to avoid provoking Hejaz and preferred Jabal Shammar to remain as a counterbalance in the Middle East. However, this campaign was fruitful for Nejd, resulting in 1,500 camels, numerous sheep, and 10,000 cartridges.