Alexander enlisted on 14th January 1915. He was 20 years and 7 months old, and was a grocer by trade. He entered the war in France on 5th June 1915 and was stationed on the D.A.A.G. Base until 15th November 1916 when he joined No 11 General Hospital. On 4th January 1917 he was admitted into his unit suffering an abscess of his left arm. He was discharged from hospital on 8th January, then went on leave for 11 days, from 25th January to 4th February 1917. On 6th April 1917 he was transferred to serve with the 141st Field Ambulance. On 8th December 1917, he accompanied
Lt J G Kramer M.O.R.C., U.S.A. to the 2nd Field Ambulance for temporary duty. On 12th December 1917, he, along with Lt J G KRAMER M.O.R.C., U.S.A. proceeded from the 2nd Field Ambulance to the 1st Bn. South Wales Borderers for temporary duty. Alexander reported that on or about 15th April 1918 he injured himself when he accidentally broke an Iodine glass bottle which buried itself into his fingers, causing the set up of inflammation. He was admitted into the hospital of this unit on 1st May 1918, then on the 9th was evacuated back to No 1 Casualty Clearing Station and then onto No 22 General Hospital the following day. He was evacuated back to England via hospital ship on the 13th May 1918. The accident resulted in Alexander loosing his right index finger. On 28th October 1918 he was posted to serve at the R.A.M.C. Depot in Blackpool. He continued to serve in the UK until 7th March 1919 when he was posted to Army Reserve.