In 1915, he joined the
Artists Rifles Officers' Training Corps and was trained at Hare Hall camp,
Gidea Park,
Essex, at the same time as the poets
Wilfred Owen and
Edward Thomas, but there is no record of them having ever met. Vaughan was then commissioned into the
Royal Warwickshire Regiment on 19 June 1916 as a
second lieutenant and sailed for France in January 1917. A fellow officer named Syd Pepper, who had seen action during the
Battle of the Somme in 1916, had convinced Vaughan to join the 1/8th battalion of the regiment and he acquired the sole remaining vacancy. During the
Battle of Passchendaele (also known as the Third Battle of Ypres) in August and September 1917 he kept a diary of his experiences with
trench warfare. He was temporary
captain of his
Company for a very short time (a few hours) while his commanding officer was wounded, until a new company commander came up to the line. Vaughan was promoted to permanent rank of captain in October 1917 and he later fought in the Italian campaign. In 1918 he returned to France where as a result of his actions in capturing the a bridge over the Sambre Canal, Vaughan was decorated with the Military Cross. ==Post-war==