The Mexican Revolution was a decade-long transformational conflict in Mexico, with consequences to this day. It saw uprisings against President Díaz, his resignation, an interim presidency, and the democratic election of a rich landowner, Francisco I. Madero in 1911. In February 1913, a military coup d'état overthrew Madero's government, with the support of the U.S., resulted in Madero's murder by agents of Federal Army General Victoriano Huerta. A coalition of anti-Huerta forces in the North, the Constitutionalist Army overseen by Venustiano Carranza, and a peasant army in the South under Emiliano Zapata, defeated the Federal Army. In 1914 that army was dissolved as an institution. Following the revolutionaries' victory against Huerta, revolutionary armies sought to broker a peaceful political solution, but the coalition splintered, plunging Mexico into civil war again. Constitutionalist general Pancho Villa, commander of the Division of the North, broke with Carranza and allied with Zapata. Carranza's best general, Alvaro Obregón, defeated Villa, his former comrade-in-arms in the battle of Celaya in 1915, and Villa's forces melted away. Carranza became the de facto head of Mexico, and the U.S. recognized his government. In 1916, the winners met at a constitutional convention to draft the Constitution of 1917, which was ratified in February 1917. Said Constitution strengthened the anticlerical provisions that were carried over from the 1857 Constitution. With amendments, it remains the governing document of Mexico. It is estimated that the war killed 900,000 of the 1910 population of 15 million.