[3][4] At the start of World War One, Williamson sought to enlist in the Britiah Army and was, at his second attempt, accepted as a private in the King's Royal Rifle Corps in January 1916.
[2][7] Williamson was also injured in April 1918 at the Villers-Bretonneux sector, when the sunken road his unit was defending was overrun by German forces.
This action became the subject of his painting A German Attack on a Wet Morning, April 1918, which Wiiliamson completed in the spring of 1919.
Although Williamson wrote an extensive set of notes to accompany the painting, he left it to others to point out that the figure in the work facing the viewer with an injured hand was a self-portrait.
[6] Other artists employed by Williamson as teachers included Graham Sutherland, Ceri Richards and Claude Rogers.