Crozier was a highly controversial figure in his day. His Great War career spanned the years from 1914 to 1918, starting as second in command of a battalion in the 36th Ulster Division, becoming its commanding officer in the Autumn of 1915. He led the battalion on the First Day on the Somme. After that, he commanded a brigade with some success for the rest of the war.
His later life was visited by controversy, and makes for highly interesting reading