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
Tampico Affair destroyed to prevent their falling under U.S. control. By the spring of 1914, diplomatic relations between the US and Mexico were strained. US President Woodrow Wilson refused to recognize the presidency of Mexican General Victoriano Huerta, who had been installed as president the previous year after Huerta and the conservative rebel General Félix Díaz, a nephew of Porfirio Díaz, had signed the Embassy Pact with the approval of US Ambassador Henry Lane Wilson, who had since been removed by the president. The instability caused by the ongoing Mexican Revolution threatened US lives and economic interests in Mexico. Although Tampico was