Promoted to lieutenant on 6 August 1890, Chetwode first saw active service in the Chin Hills expedition in Burma from 1892 to 1893 and was promoted to captain on 7 February 1897. He served in the Second Boer War where he took part in the actions at Reitfontein in October 1899, Ladysmith in December 1899, Laing's Nek in June 1900 and Belfast in August 1900: he was twice mentioned in despatches and was awarded the Distinguished Service Order. Promoted to major on 21 December 1901, he stayed in South Africa until the end of hostilities. The war ended with the Peace of Vereeniging in late May 1902, and the following month Chetwode returned home in the "SS Tagus", arriving at Southampton in July. He succeeded as 7th Baronet in 1905.