Pérochon started a new teaching post in 1914, at Vouillé. Later in the year he was mobilised, and was sent to the Front. He had a heart attack there and was “repatriated rapidly” back to Parthenay. The website of La Tour Nivelle, the Musée d’École et Maison Littéraire Ernest Pérochon, in Courlay, from which I draw this information, notes that his few weeks at the front rendered him even more pessimistic about mankind than before. He was inspired to write, much later, one of his greatest successes, the novel called Les Gardiennes (1925). This was a homage to the women who, left behind on the farm, worked so hard to keep those farms running and to feed the country and the soldiers on the Front.
I have not yet found the volume of essays on Pérochon, edited by Huguette Gelot and Paul Vernois, published by the Société Historique et Scientifique de Deux-Sèvres in Niort, which is pictured on the website mentioned above.