During this period, the Marjit Singh and his three brothers settled in the neighbouring Cachar and made multiple unsuccessful attempts to oust the Burmese.

The force was eventually increased to 2000 men, including cavalry, infantry and artillery, under the name 'Manipur Levy'.

[9] Along with Gambhir Singh and Pemberton, a force of 500 men left Sylhet on 17 May 1825 and arrived in the Manipur Valley on 10 June.

[10][11] More troops were brought in in December 1825, commanded by Captain Grant, and an advance was made to the Kabaw Valley.

[12] The Anglo-Burmese War was soon concluded with the signing of the Treaty of Yandabo, and the Burmese agreed to relinquish control over Manipur.

[16] Meanwhile, the British sent Major Henry Burney as the Resident to Burma, who discovered, upon his arrival at Ava, that tensions were very high regarding the Kabaw Valley.

[18][19] Based on the force of Burney's argument as well as the apparent seriousness of the Burmese claim, the governor-general acceded to the cession of Kabaw Valley to Burma.

[21] Grant and Pemberton were dispatched to define the boundary between Manipur and Burma along the Yomadong range, where it still lies.

The Burmese also asked for consultation with the tribes living on the eastern slope of the Yomadong range, which was also denied for being inconsistent with the instructions of the British government.

Pemberton's inquiries showed that the southern boundary of Kabaw Valley was at a river called Numsailung by Manipuris (Namsaweng in Burmese and Tuipu in Kuki-Chin).

So he included in the agreement an imaginary line running west from the point where Numsailung enters the plains, across the mountains up to the Manipur River.

[23] But it did influence the British thinking in later times and, when a proper boundary between Manipur and Chin Hills was defined in 1894, it was drawn very close to Pemberton's imaginary line.

[25] The couple had a son, Robert Charles Boileau Pemberton, who also served in the Indian Army and rose to Major-General.