During the second year of the First World War in 1915, Suart enlisted as a private in the South Lancashire Regiment. He transferred to the Royal Warwickshire Regiment later that year and went on to see action at High Wood, Guillemont, Flers-Courcelette, Morval, Le Transloy, Arras and the Third Battle of Ypres during 1916 and 1917. His division was transferred to the Italian Front following the Third Battle of Ypres, but returned to France in April 1918. Suart was killed during a German counter-attack near Gouzeaucourt on 27 September 1918, just over six weeks before the Armistice. He is commemorated on the Vis-en-Artois Memorial.