Salmond joined the British Army, undertaking his officer training at Royal Military Academy Woolwich around 1897. He was commissioned into the Royal Artillery on 23 June 1898 and saw active service during the Second Boer War. He took part in the relief of Ladysmith and the operations on the Tugela Heights. He received he Queen's Medal and seven clasps, then on 10 November 1900 he was sent to China and gained a medal for the operations during the Boxer Rebellion there. He was seconded to study Japanese on 2 May 1905 and promoted to captain on 2 December 1905. He was then appointed Adjutant with the Royal Field Artillery on 4 February 1908. Then in 1911 he attended the Staff College, Camberley.