Stanley was educated at Guy's Hospital, qualifying M.R.C.S., L.R.C.P. in November 1914. He attended the University of London, Officer Training Corps, and also joined the R.A.M.C. (T.F.) at the rank of Lieutenant on 17th October 1914. He was sent to France soon after. Stanley was promoted to Captain on 17th April 1915. He was serving as medical officer to the South Staffordshire Regiment when he was awarded the Military Cross “For conspicuous gallantry and devotion to duty. He worked continuously for ten hours under very heavy fire, and was responsible for saving many lives. He displayed great courage and determination throughout. He has on many previous occasions done fine work.” He served under the rank of acting major from 24th May - 6th October 1918, and gained a permanent regular army commission at the rank of captain on 1st June 1918. Stanley and his party were gassed by a H.E. and mustard gas shell of large calibre, which landed in the doorway of his dug-out. He did recover at the time, but died a few days later from broncho-pneumonia.