Chumbi Valley and Gangtok The next day, 26September, the British advanced along the Ammo Chu, and bivouacked for the night at Myatong (Yatung). The Tibetans were disorganized and did not oppose the enemy's progress. Meanwhile, Graham found it necessary to advance to Gangtok, the capital of Sikkim, where the pro-Tibetan party had ousted the pro-Indian opposition. Colonel Mitchell, with 150 men from the 13th Bengal Infantry, marched to the city on the 23 September. Convention of Calcutta After the advance on Chumbi and Gangtok, military operations stalled. On 21December, the Chinese resident in Lhasa arrived at Gnathong and negotiations began, but no agreement was reached so the Amban returned to Rinchingong where he received orders to wait for Mr. T. H. Hart, of the Chinese Imperial Customs Service, who finally arrived to Gnathong on 22March 1889. Eventually the Anglo-Chinese Convention of Calcutta was signed on 17March 1890 at Kolkata, which established the Tibetan renunciation of suzerainty over Sikkim, and delimited the border between Tibet and Sikkim. See also British expedition to Tibet Notes References Scholarly sources p. 212. Matteo Miele, The British Expedition to Sikkim of 1888: The Bhutanese Role, West Bohemian Historical Review, 2018, VIII, 2. Historical sources Wars involving Tibet Wars involving British India Wars involving the Qing dynasty Wars involving the United Kingdom Conflicts in 1888 1888 in China 1888 in India History of Sikkim Military expeditions Expeditions from the United Kingdom Expeditions from India