During World War I, J. Gresham Machen worked with the YMCA behind the lines in France. From the conclusion of Letters from the Front: J. Gresham Machen’s Correspondence from World War I, ed. Barry Waugh (2012), we have the following paragraph on the influence World War I had on Machen.
War provides an opportunity for people to do things that they would never choose to do on their own. Though J. Gresham Machen’s service was that of a non-combatant, he was still faced with conditions that required a considerable ability to adapt to dangerous and culturally different situations. In France, Machen worshipped God as he had the opportunity in churches and special services. Surely, he would rather have been home in a Presbyterian