Mexican Revolution revolution was in 1914, during the "Ypiranga" incident. When United States intelligence agents received word that the "Ypiranga", a German merchant ship, contained illegal firepower for Huerta, President Wilson ordered American troops to the port of Veracruz to stop the ship from docking. Wilson never actually declared war on Mexico. The United States skirmished with Huerta's troops in Veracruz. The "Ypiranga" successfully docked at another port and unloaded the arms, which greatly angered Wilson. The ABC Powers arbitrated and U.S. troops left Mexican soil, but the incident added to already tense Mexican-American relations. In 1916, in retaliation for Pancho Villa's
21-gun salute bloodshed of the revolution at its border, Mexico was forced to seek arms from European, and to a lesser extent Asian countries. During the occupation, a large German arms shipment aboard the SS Ypiranga was illegally seized, before being released and turned away by the U.S. occupation force. These events ultimately drove a wedge between Mexican-U.S. and German-U.S. relations, and after the start of World War I on 28 July 1914, would cause Germany to seek to influence Mexico into declaring war on the United States, in order to halt U.S. arms shipments to the Allies, and attempt to prevent