Everything seemed satisfactory and the Khan promised to visit Quetta to pay his salaams to Shah Shujia. Sir Alexander Burnes, who had preceded him, was robbed on the way of the draft of the treaty signed by the Khan. Treacherous Mulla Mahommed Hasan did not fail to impress upon the British that the Khan had given directions to have the treaty stolen, and had, furthermore, prevented Mehrab from proceeding to Quetta. The hostility of the Khan being evident, it was resolved to send a punitive expedition to Kelat to give the Khan a lesson.
On the 13th of November, 1839, the town was stormed and taken by a detachment of General Wiltshire's brigade, Mehrab Khan was killed and his son fled, while the Khan's Minister was made prisoner and his treachery proved.
Shah Nawaz Khan—a youth of fourteen, a direct descendant in the male line from Mahabat Khan—was set up by the British as the future Khan of Kelat. The provinces of Sarawan and Kach Gandava were annexed to the dominions of the Amir of Afghanistan.
Mehrab's son, Nasir Khan, the rightful successor to the rule of Kelat, headed a revolution; Shah Nawaz was deposed, the British representative at Kelat was killed, and Nasir Khan was eventually established in power by the British, the two provinces restored to him, and a new treaty concluded with him on October 6th, 1841.
This treaty acknowledged Nasir Khan and his descendants the vassals of the King of Cabul; allowed if necessary, the Honourable Company's or Shah Shujia's troops to be stationed in any positions they deemed advisable in any part of his territory; and declared that a British resident officer's advice should always be followed. Caravans into Afghanistan from the Indus as well as from Soumiani port were to be protected from attacks, and no undue exactions imposed on them; the British Government undertook to afford Nasir Khan protection in case of attack; while Nasir Khan bound himself to provide for the support of Shah Nawaz whom he had deposed.
This treaty became useless after the retirement from Cabul, and it was found necessary to negotiate a new agreement dated 4th of May, 1854, which annulled the treaty of October 6th, 1841, enjoined perpetual friendship between the British Government and the Khan of Kelat, his heirs and successors, and bound Nasir Khan and successive Khans "to oppose to their utmost all enemies of the British Government with whom he must act in subordinate co-operation, and not enter, without consent, into negotiations with foreign States."
British troops might occupy, if necessary, any position they thought advisable in the Kelat territory, and British subjects and merchants from Sindh or the coast to Afghanistan were to be protected against outrage, plunder and exactions. A transit duty, however, was to be imposed at the rate of six rupees on each camel-load from the coast to the northern frontier, and 5 rupees from Shikarpur to the same frontier.
To aid Nasir Khan, his heirs and successors, in the fulfilment of these obligations, and on condition of faithful performance of them, the British Government bound itself to pay to Mir Nasir Khan, his heirs and successors, an annual subsidy of 50,000 Company's rupees. If, however, the conditions required were not fulfilled year by year the Government would stop the payment of the annual subsidy.
When Nasir Khan died in 1857, his brother, his son, and his half-brother claimed the succession, and the latter, Khudadad Khan, a boy of ten, was elected by the chiefs; but had it not been for the support given him by the British Government, who for four successive years paid him an additional 50,000 rupees besides the 50,000 stipulated in the agreement, in order to help him to suppress the rebellious Marris tribe, he could not have maintained his position.
The leading Kelat chiefs, dissatisfied with their ruler, elected Sherdil Khan, Khudadad's cousin, as Khan of Kelat, but he was murdered the following year, 1864, and the banished ruler reinstated in his former position. Previous to his banishment, in 1862, a proper agreement was signed defining the boundary line between British India and the Khan's territory, but it was not till 1887 that matters regarding it were absolutely settled.