Brother of 2951 Private Ernest George Lewis, 2357 Extra Regimental Sergeant Frederick James Lewis, 1616 Driver George Albion Lewis, 1772 Driver Thomas Arthur Lewis and 1773 Driver Richard Franklin Lewis.
William Lewis arrived in Egypt in December 1915. In April 1916 his 2nd Remount Unit was reduced by half and merged with the similarly reduced 1st Remount Unit to form a single unit. No longer required, he was returned to Australia and was discharged in June.