United States involvement in the Mexican Revolution with its diplomatic and economic rivals in Mexico, particularly Great Britain and Germany, meant that foreign powers affected the way the Mexican situation played out. When U.S. agents discovered that the German merchant ship, the "Ypiranga", was carrying arms to Huerta's regime, President Wilson ordered troops to the port of Veracruz to stop the ship from docking. The U.S. did not declare war on Mexico city but the U.S. troops carried out a skirmish against Huerta's forces in Veracruz. The "Ypiranga" managed to dock at another port, which infuriated Wilson. On April 9, 1914, Mexican officials in the port of
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