structural:summarization, structural:expansion
Meeting of the winners, then civil war: 1914–1915

With Huerta's ouster in July 1914 and the dissolution of the Federal Army in August, the revolutionary factions agreed to meet and make "a last-ditch effort to avert more intense warfare than that which unseated Huerta". Commander of the Division of the North, Pancho Villa, and the Division of the Northeast, Pablo González had drawn up the Pact of Torreón in early July, pushing for a more radical agenda than Carranza's Plan of Guadalupe. It also called for a meeting of revolutionary generals to decide Mexico's political future.

Carranza called for a meeting in October 1914 Mexico City, which he now controlled with Obregón, but other revolutionaries opposed to Carranza's influence successfully moved the venue to Aguascalientes. The Convention of Aguascalientes did not, in fact, reconcile the various victorious factions in the Mexican Revolution. The break between Carranza and Villa became definitive during the Convention. "Carranza spurned it, and Villa effectively hijacked it. Mexico's lesser caudillos were forced to choose" between those two forces. It was a brief pause in revolutionary violence before another all-out period of civil war ensued.

Carranza had expected to be confirmed in his position as First Chief of revolutionary forces, but his supporters "lost control of the proceedings". Opposition to Carranza was strongest in areas where there were popular and fierce demands for reform, particularly in Chihuahua where Villa was powerful, and in Morelos where Zapata held sway. The Convention of Aguascalientes brought that opposition out in an open forum.

The revolutionary generals of the Convention called on Carranza to resign executive power. Although he agreed to do so, he laid out conditions for it. He would resign if both Pancho Villa and Emiliano Zapata, his main rivals for power, would resign and go into exile, and that there should be a so-called pre-constitutionalist government "that would take charge of carrying out the social and political reforms the country needs before a fully constitutional government is re-established."

Rather than First Chief Carranza being named president of Mexico at the convention, General Eulalio Gutiérrez was chosen for a term of 20 days. The Convention declared Carranza in rebellion against it. Civil war resumed, this time between revolutionary armies that had fought in a united cause to oust Huerta in 1913–1914. During the Convention, Constitutionalist General Álvaro Obregón had attempted to be a moderating force and had been the one to convey the Convention's call for Carranza to resign.

The lines were now drawn. When the Convention forces declared Carranza in rebellion against it, Obregón supported Carranza rather than Villa and Zapata. Villa and Zapata went into a loose alliance. Their forces moved separately on Mexico City, and took it when Carranza's forces evacuated it in December 1914 for Veracruz. The famous picture of Zapata and Villa in the National Palace, with Villa sitting in the presidential chair, is a classic image of the Revolution. Villa is reported to have said to Zapata that the presidential chair "is too big for us".

In practice, the alliance between Villa and Zapata as the Army of the Convention did not function beyond this initial victory against the Constitutionalists. Villa and Zapata left the capital, with Zapata returning to his southern stronghold in Morelos, where he continued to engage in warfare under the Plan of Ayala. Lacking a firm center of power and leadership, the Convention government was plagued by instability. Villa was the real power emerging from the Convention, and he prepared to strengthen his position by winning a decisive victory against the Constitutionalist Army.

Villa had a well-earned reputation as a fierce and successful general, and the combination of forces arrayed against Carranza by Villa, other northern generals and Zapata was larger than the Constitutionalist Army, so it was not at all clear that Carranza's faction would prevail. He did have the advantage of the loyalty of General Álvaro Obregón. Despite Obregón's moderating actions at the Convention of Aguascalientes, even trying to persuade Carranza to resign his position, he ultimately sided with Carranza.

Another advantage of Carranza's position was the Constitutionalists' control of Veracruz, even though the United States still occupied it. The United States had concluded that both Villa and Zapata were too radical and hostile to its interests and sided with the moderate Carranza in the factional fighting. The U.S. timed its exit from Veracruz, brokered at the Niagara Falls peace conference, to benefit Carranza and allowed munitions to flow to the Constitutionalists. The U.S. granted Carranza's government diplomatic recognition in October 1915.

The rival armies of Villa and Obregón clashed in April 1915 in the Battle of Celaya, which lasted from the sixth to the 15th. The frontal cavalry charges of Villa's forces were met by the shrewd, modern military tactics of Obregón. The victory of the Constitutionalists was complete, and Carranza emerged as the political leader of Mexico with a victorious army to keep him in that position. Villa retreated north. Carranza and the Constitutionalists consolidated their position as the winning faction, with Zapata remaining a threat until his assassination in 1919. Villa also remained a threat to the Constitutionalists, complicating their relationship with the United States when elements of Villa's forces raided Columbus, New Mexico, in March 1916, prompting the U.S. to launch a punitive expedition into Mexico in an unsuccessful attempt to capture him.