On November 6, 1903, Britain approved the Diplomatic Corps of the British Indian Army to proceeds towards Gyantse via the Chumbi Valley, marking the second time the British army invaded Tibet. The British army, commanded by Brigadier General MacDonald, had more than 2,000 men and was equipped with newer weaponry. They crossed the Zanli Pass on December 10, beginning the second British war against Tibet since 1888.

On April 11, 1904, the British Army arrived in Gyantse. On August 3, they invaded the Tibetan capital of Lhasa. In Lhasa, the British army plundered and looted several precious cultural relics and religious texts. British Army Colonel Younghusband forced local officials to sign the “Lhasa Convention” on September 7, 1904.