The document summarizes Mexico's history from 1920-1940. After the deaths of revolutionary leaders Zapata and Carranza, Obregon became president and stabilized the country by incorporating the military into the federal army. However, the succession of Obregon led to conflict between the Catholic Church and President Calles, resulting in the Cristero Rebellion from 1926-1929. Later presidents like Portis Gil resolved disputes with the Catholic Church and improved education, while Abelardo Rodriguez distanced the presidency from Calles and focused on workers' rights.