Birdwood was commissioned as a second lieutenant on to the Unattached List, Indian Army on 21 December 1917. In France he was Aide-de-Camp to the General Officer Commanding the Australian Corps and 5th Army, his father, from 10 March 1918 to 28 February 1919. For his service he was Mentioned in Despatches. He was decorated with the Order of Aviz of Portugal. He arrived in India on 10 April 1919, was appointed to the Indian Army on 15 April 1919 and posted to the King Edward VII's Own Lancers of the Indian Army. As per the London Gazette of 12 September 1919 he was promoted lieutenant, antedated to 22 December 1918, but not until the French Republic conferred the Chevalier de la Légion d'honneur for helping save La Patrie. In the same year he fought in the Waziristan Campaign between 1919 and 1920. In February 1920 he was promoted Acting Captain whilst attached to the 2/76th Punjabis, additionally being made Adjutant in July 1920. Birdwood returned to the 11th KEO Lancers by March 1921, by which time they had amalgamated with the 12th Cavalry to form 5th King Edward's Own Probyn's Horse, so named after a secretary to Queen Victoria. He was eventually promoted to captain on 21 December 1921. Between 1923 and 1925 he served on the North West Frontier with various units of the Frontier Corps. He was Aide-de-Camp to the Commander-in-Chief at India, his father, between 13 May 1929 and 29 November 1930. He was appointed British Officer in Charge of the King's Indian Orderly Officers in 1932, promoted to major on 21 December 1935. He fought in the Waziristan Campaign again between 1936 and 1937. He was appointed a Squadron Commander in Probyn's Horse 15 January 1938, but was appointed Commandant of the Governors Body Guard, Bombay on 21 March 1938. He was again appointed British Officer in Charge of the King's Indian Orderly Officers in 1939. For this service he was invested as a Member of the Royal Victorian Order in 1939. During the Second World War, he returned with Probyn's Horse in August 1940 and rose to become temporary second in command by April 1942, later he served on the Staff. He was promoted to lieutenant colonel on 21 December 1943 but was retired due to ill-health on 4 June 1945.
Personal life
He married, firstly, Elizabeth Vere Drummond Ogilvie, daughter of Lieutenant Colonel Sir George Drummond Ogilvie and Lorna Rome, on 7 March 1931 at Delhi, India. The couple had a son and daughter; they divorced in 1954. In the meantime, he had succeeded to his father's titles on 17 May 1951. He married, secondly, Joan Pollack Graham, by then known as Jane, daughter of Christopher Norman Graham, on 22 February 1954. After his death, Lady Birdwood became an activist on the far-right of British politics. His son from his first marriage, Mark William Ogilvie Birdwood, succeeded to the title.
