Task: Question Generation
Input (English): Villa and Carranza had different political goals causing Villa to become an enemy of Carranza. After Carranza took control in 1914, Villa and other revolutionaries who opposed him met at what was called the Convention of Aguascalientes. The convention deposed Carranza in favor of Eulalio Gutiérrez. In the winter of 1914 Villa's and Zapata's troops entered and occupied Mexico City. Villa was forced from the city in early 1915 and attacked the forces of Gen. Obregón at the Battle of Celaya and was badly defeated in the bloodiest battle of the revolution, with thousands dead. With the defeat of Villa, Carranza seized power. A short time later the United States recognized Carranza as president of Mexico. Even though Villa's forces were badly depleted by his loss at Celaya, he continued his fight against the Carranza government. Finally, in 1920, Obregón—who had defeated him at Celaya—finally reached an agreement with Villa end his rebellion.
Output (English): At which battle was Obregon badly defeated?