William as educated at Newton Abbott College; and at University College Hospital, where he obtained his M.R.C.S., L.R.C.P in 1891, and his M.B. in 1894. He held the post of house physician at the Brompton Hospital, whilst also serving with the Territorial Force. William served in the South African War 1900-1901 - taking part in the operations in the Transvaal in May and June 1900; the operations in the Transvaal, east of Pretoria from July to 29th November 1900; the operations in Orange River Colony from May to 29th November 1900; operations in Cape Colony, North of Orange River; operations in Orange River Colony from 30th November 1900 to May 1901, and those in Capt Colony. For this he gained the Queen’s Medal with four clasps. On 10th July 1901, he obtained a commission as Hon. Lieutenant in the 3rd Bn. Royal Fusiliers. He was promoted to Captain, and was attached to the 3rd Bn London Regiment on 20th September 1914. He then went to the Dardanelles, entering the war in Gallipoli from August 1915. He died at Sulva Bay. William was the only surviving son of John Bryant Rielly of Rangoon; and the husband of Annie Julia (2nd daughter of James Stuart) of 4 Nassau Road, Barnes - married at Barnes Paris Church on 9th July 1904.