US President Woodrow Wilson backed the demand, and the conflict escalated when the Americans occupied the port city of Veracruz for more than six months.

Several US Navy warships commanded by Rear Admiral Henry T. Mayo were deployed off the coast for the stated purpose of protecting US citizens and property.

Additionally, sailors from the US gunboat and two cruisers, anchored off Tampico in the Pánuco River, went ashore each day to play baseball.

[2] On 6 April, Constitutionalist rebel forces, under the command of Col. Emiliano J. Nafarrete, occupied La Barra, Doña Cecilia, and Arbol Grande.

Earle, accompanied by Clarence Miller, met with Zaragoza who apologized, explaining his men were "evidently ignorant of the first laws of war."

Mayo had Commander William A. Moffett deliver a note to Zaragoza stating, "taking men from a boat flying the American flag is a hostile act, not to be excused."

When Wilson heard of the matter from Secretary of State William Jennings Bryan, Wilson responded, "Mayo could not have done otherwise," and further, "...unless the guilty persons are promptly punished consequences of gravest sort might ensue..."[2]: 32 Nelson J. O'Shaughnessy, the US Chargé d'Affaires ad interim[7] in Mexico City, was informed of the incident by Roberto A. Esteva Ruiz, Mexico's Ministry of Foreign Relations, on 10 April.

O'Shaughnessy then released the Mexican account to the Associated Press in Mexico, misstating that the arrested Americans involved were Marines, not sailors, and that they had been "paraded" through the streets of Tampico.

Huerta called these "humiliating terms...carrying courtesy to that point would be equivalent to accepting the sovereignty of a foreign state to the derogation of national dignity and decorum, which the president is disposed to have respected in any case."

On 14 April, Wilson ordered the Atlantic Fleet, under the command of Vice Admiral Charles Johnston Badger, to Mexican waters.

On 16 April, Washington was notified that Huerta had agreed to a simultaneous salute, signifying "satisfaction with which the two countries see the happy end of a conflict which has at no time been really serious."

On 18 April, Wilson stated he would see Congress, "with a view of taking such actions as may be necessary to enforce the respect due to the nation's flag," if Mexico did not fire the salute by the next day.

Wilson received Congressional approval that evening, and ordered landings at Veracruz, so as to seize the Custom house, and intercept an expected arms shipment for Huerta's forces.

[10][11] On the Pacific Coast of Mexico, US Naval units were monitoring the fight between Huerta's forces and the rebels while they protected US citizens and interests.

"[12] USS Cheyenne was sent from San Diego, California, to Ensenada with orders to protect US lives at any cost, including capturing the port if necessary.

[15][16] Ultimately, the US military transport ship USS Buford sailed from San Francisco in early May and made stops at numerous ports on the west coast of Mexico to pick up additional American refugees.

The British interception of Zimmermann's telegram and the German unrestricted submarine warfare against US merchant ships soon afterward, were effectively both final justifications that President Wilson needed to request a declaration of war against Germany, in April 1917.

[19] Anti-American sentiment in Mexico from the Tampico incident was the chief reason that the Mexican government remained neutral in World War I.

[23][24] The relatively new Mexican president, Venustiano Carranza, threatened to destroy the oil fields in case the Marines landed there.