On April 21, 1914, before the U.S. Congress had the opportunity to approve President Wilsonís request for authority to intervene in Mexico, the president acted. Wilson had received word that a German ship was approaching the port city of Vera Cruz and was laden with a huge arms shipment for the Victoriano Huerta regime. The president ordered the immediate occupation of Vera Cruz. Fighting was fierce; more than 300 Mexicans and about 90 Americans were killed.
This blatantly provocative act served to unify the previously divided Mexicans. Venustiano Carranza offered support to his bitter rival, Huerta, then both demanded the immediate removal of American forces. The Mexican government then severed diplomatic relations with the United States.
Wilson had seriously misread the situation and accepted a mediation offer from the South American nations of Argentina, Brazil and Chile in the so-called ABC Conference.