In August 1914 Marie Guillot wrote to Pierre Monatte: "What frightens me more than all the carnage is the wave of hatred that always rises higher, and deflects the energy of the workers from their goal. During the years of conflict Guillot continued in the same stubborn way to express pacifist ideas wherever she could. She was comforted by Romain Rolland's "Au-dessus de la mêlée" (Above the fray – September 1914), by the attitude of Pierre Monatte with whom she corresponded throughout the war, and by the pronouncements of other teachers for peace. She was questioned several times but was not arrested during the war. After the war Marie Guillot was active in union work. From 7 to 10 August 1919 she participated in Tours in the Congress of the National Federation of teachers unions. From 15 to 21 September 1919, she participated in the 14th Congress of the CGT in Lyon, where she was among the "revolutionary" minority of syndicalists. In January 1920, she was elected Secretary General of the Committee of revolutionary syndicalists of Education. In August of the same year she participated at Bordeaux in the fourteenth congress of the Federation of teachers' unions. Marie Guillot was one of 350 delegates representing 12,000 members divided into 68 unions. However, the right to organize was still denied to civil servants, including teachers. The secretary of the federation, Louis Bouët, lost his job in July 31. This was the third time in the history of the young teachers unionism that a federal secretary was revoked. During the years 1919–1921, several education trade unionists also underwent investigation and sanction. Marie Guillot, leader of the revolutionary syndicalist committee of Saône-et-Loire was brought before a disciplinary council in January 1921. She was dismissed on 25 April 1921 on the grounds that "acts of revolutionary propaganda carried out by Mlle Marie Guillot are incompatible with the functions of a public teacher." For good measure, the school of Saint-Martin-d'Auxy, emptied of its students by demographic decline and local intrigues, was closed. Guillot's friends from "La Vie ouvrière" provided editorial work to those who found themselves without pay. A solidarity subscription collected the equivalent of eight months of her teacher's salary. She donated a large part to her union to cover the cost of legal action. But her activism increased in her free time.