Sikkim Expedition - 1888. Britain and Tibet competed for influence in the Himalayan state of Sikkim, in North East India. Open warfare occurred when Thutob Namgyal, the Chogyal of Sikkim, started to favor Tibet. A force was dispatched under the command of Brigadier-General Thomas Graham, RA. Although Tibetan forces greatly outnumbered the British, their matchlocks and bows were no match for modern weapons. After defeat, Tibet ceded suzerainty of Sikkim in the 1890 convention of Calcutta.