Abdur Rahman ruled Afghanistan for over 20 years until his death in 1902. The Treaty of Gandamak he signed in 1880 outlived him but was broken by Amir Amanullah Khan in 1919. Within weeks of his succession the new Amir declared independence and proclaimed 'jihad', or Holy War. By encouraging revolt on the North West Frontier he hoped to seize the old Afghan provinces west of the River Indus that had been captured by the Sikhs many years before. Amanullah believed that the British would be too war-weary to resist. A detachment of Afghan troops entered British India.
Unnerved by Amanullah's alliance with the new Bolshevik regime in Russia and his support of Indian nationalists, the British government mobilised the Indian Army. As before, fighting on the ground focused on the three main mountain passes. In the Khyber Pass a division defeated a superior Afghan force that had occupied Bagh and attacked Landi Kotal, forcing them back across the border and occupying Dakka on 13 May 1919.
In southern Baluchistan the British successfully stormed the Afghan fortress of Spin Baldak on 27 May 1919. This fort guarded the strategically vital road from Kandahar. Its capture reduced the chance of an Afghan invasion by that route. Over 200 of its 500-strong garrison of Afghan regulars, many of whom were armed only with single shot Martini-Henry rifles, were killed in the action. The British lost 18 killed and 40 wounded. Fighting also occurred in the tribal districts of Chitral in the far north, but this was successfully contained.
Airpower played a key role during the war and the subsequent revolt in Waziristan. Five Royal Air Force (RAF) squadrons of BE2Cs, Bristol F2Bs, De Haviland DH9As and De Haviland DH-bombers were used in strafing and bombing attacks on the rebellious frontier tribes and on targets in Afghanistan itself, including Kabul and Jalalabad. The attacks on Afghan towns, although small scale, helped bring King Amanullah to the negotiating table.
In Kurram the situation became critical when the militia in adjacent Waziristan, stirred up by the Afghan government, mutinied against their British employers. Major Guy Hamilton Russell, commander of the South Waziristan Militia, made a fighting withdrawal, but the garrison at Thal guarding the Kurram Pass was cut off. Although besieged and attacked by an Afghan army the Thal garrison held out for a week until it was relieved by a column from Peshawar under Brigadier-General Reginald Dyer.
Amanullah Khan ordered a ceasefire on 3 June 1919. His ambitious plans to reclaim Peshawar and throw the British out of India had failed. On the other hand the Treaty of Rawalpindi (1919) that brought the war to an end did recognise full Afghan independence and finally gave the Afghans the right to conduct their own foreign affairs. This may have been Amanullah’s real goal. For the British, the Durand Line, long a contentious issue between the two nations, was reaffirmed as the political boundary separating Afghanistan from the North West Frontier. The Afghans also agreed to stop interfering with the tribes on the British side of the line.
Neither Afghan Amirs nor British governments had ever really controlled the fiercely independent tribes in the mountainous borderlands between Afghanistan and India. Between 1880 and 1919 the Indian Army mounted dozens of operations to punish hill tribes who raided lowland villages, but the cycle of violence continued. Immediately following the Third Afghan War, Wazir and Mahsud tribes launched attacks on British garrisons. Fearsome warriors, they were on the look out for opportunities to loot and pillage. They were also angered by rumours that Waziristan was to be handed over to Afghanistan in post-war talks.
Although there was fighting on the ground, it was the British bombing of Wazir and Mahsud villages that brought the conflict to an end in 1920. Nevertheless, over 10,000 troops from the Indian Army took part in the campaign to re-establish British control of the border areas. The difficulties they experienced made the British change their policy on the North-West Frontier. Until 1947 Waziristan was permanently garrisoned with experienced, regular troops who worked closely with local militia units. The British also embarked on a road building programme to improve military access to the tribal areas.