A truce was negotiated with the assistance of U.S. Ambassador Dwight Whitney Morrow. Calles, however, did not abide by the terms of the truce – in violation of its terms, he had approximately 500 Cristero leaders and 5,000 other Cristeros shot, frequently in their homes in front of their spouses and children. Particularly offensive to Catholics after the supposed truce was Calles' insistence on a complete state monopoly on education, suppressing all Catholic education and introducing "socialist" education in its place: "We must enter and take possession of the mind of childhood, the mind of youth". The persecution continued as Calles maintained control under his Maximato and did not relent until 1940, when President Manuel Ávila Camacho, a believing Catholic, took office. This attempt to indoctrinate the youth in atheism was begun in 1934 by amending Article 3 to the Mexican Constitution to eradicate religion by mandating "socialist education", which "in addition to removing all religious doctrine" would "combat fanaticism and prejudices", "build in the youth a rational and exact concept of the universe and of social life". In 1946 this "socialist education" was removed from the constitution and the document returned to the less egregious generalized secular education.