His nephew John McEwan had been killed in the Battle of Loos on 26 November 1915 where he was serving with the Black Watch Royal Highlanders. One source says it was 21 July 1917 when his own son, William McEwan junior enlisted with the US Army Medical Corps. Here he is on the right hand side, in an earlier clipping from the Press and Sun-Bulletin (Binghamton, New York) of Tuesday, April 17, 1917, just 11 days after the US decided to enter the war.
Within weeks, William senior had been approached by the US Army to become a singing instructor. He joined the War Department Commission on Training Camp Activities at Camp Jackson near Columbia, South Carolina. He was attached to the quartermaster corps at large, and was aide to Brigadier General Francis Henry French, the commandant. McEwan is mentioned on p197 and p207 of this book about the camp. He also features in this 1919 book: Camp Music Division of the War Department, and in this 2016 book, Singing, Soldiering and Sheet Music in America during the First World War.
The links and similarities between William McEwan and Harry Lauder are very interesting; Lauder’s son John was killed on 28 December 1916, a story told in his book A Minstrel in France (online here). The clipping below is from 29 August 1917:
He was still singing at evangelistic missions in Tennessee, with 'My Ain Countrie' still a big favourite. This clipping is from 21 August 1917:
In September 1917 McEwan reported of leading a ‘Colored Soldier Community Sing’ with 10,000 men in attendance. Interestingly he found that the Black soldiers were ‘enthusiastic and appreciate being taught new songs … the only time I spend on them is to improve their rhythm and keep them from over-harmonizing’. What a sound that must have been! While at Camp Jackson, McEwan compiled two ‘broadsides’ – Songs the Soldiers and Sailors Sing (online here) and Hike Songs No. 2.
He was then moved north to Camp Devens in Massachusetts; this clipping is from 4 October 1917:
This from 3 December 1917 - an attempt to form the world’s biggest men’s choir, and also a near-death experience in a train crash, reminiscent of the crash which had killed hymnwriter Philip Bliss in 1876:
On 19 March 1918 in Camp Devens newspaper Trench and Camp, he explained some of his personal background, and prepared to cross the Atlantic once again:
In a Roll of Honour article of 20 May 1918, the Press and Sun-Bulletin printed the names of father and son together:
On 7 October of that year, McEwan was back home, and expressing his frustrations on what seemed like a lack of public support for the war effort.
But just over a month later, on 11 November 1918, the war was over, and the MacEwans were back home. But sadly the family had only a few months left together, as William's wife Jeanie died on 25 July 1919.