William was born in 1892 in New Tredegar, Mons, to Thomas John and Isabella of 24, Birch Grove, Tirphil. William James Rees was one of at least four children that were born to them. Thomas and Isabella were married at Bedwellty in the second quarter of 1891. They had the following children: William James Rees, born in 1892, Mary Eleanor Rees, born in 1894, Thomas Rees, born in 1895 and Lodwick M Rees who was born in 1898.
William enlisted in Newport and disembarked in France to join the regiment in the field on 17th October 1915. William died of wounds to the stomach on the 14 August 1918 and was buried in the Crouy Military Cemetery, plot VI.23.C. Crouy-sur-Somme, France.
Sources:
17th Lancers War Diary
http://newtredegar-ww1.org.uk/html/w_rees1.htm