Born on 6th May 1892 Brigadier Buchanan was the eldest son of Robert Eccles Buchanan and his wife Ethel Maud, (nee Williams). At that stage the family lived at Harding Street, Londonderry. They subsequently moved to Templemore Park. The young Buchanan entered Foyle's preparatory school in 1899 where he was joined by his younger brother Richard Brendan Buchanan.
He completed his education at Portora Royal School before joining the Royal Engineers. As a career soldier he served in India, Mesopotamia, Singapore, Malta, North Africa and Italy. He was wounded on two occasions during the Great War and was awarded the DSO. After the Second World War he was Director of Fortifications at the War Office. His promotion to the rank of Brigadier appears in the Gazette of 14th November 1947. Brigadier Buchanan died at Halesmere Surrey on 13th September 1979. His brother , a Second Lieutenant with the Royal Scots Fusiliers, also served during the Great War but fell at Galipoli on 20th June 1915.