On September 23, 1914, Pancho Villa declared war against Venustiano Carranza. Disagreements over the leadership of Mexico after the ouster of Victoriano Huerta in July precipitated the third, most violent phase of the Mexican Revolution.
A major front in this renewed civil war opened on the border between Arizona and Sonora in the tiny hamlet of Naco. The Villista governor Jose Maria Maytorena had pushed the forces of Carranza against the international border and besieged the town. The Carranzista commanders Benjamin Hill and Plutarco Elias Calles dug in as they were able to receive supplies from the American side of the border. Heavy fighting on the Mexican side caused stray bullets to pound the American side of the town. As a result, the 10th U.S. Cavalry with reinforcements from the 9th took up positions on October 7. The 12th Infantry from Nogales, Arizona joined the cavalry units that had been dispatched from Fort Huachuca near Tucson and Fort Douglas. The commander of the Southern Department of the U.S. army at Fort Sam Houston, Brigadier General Tasker Howard Bliss, had overall command. The American units dug in and observed the fighting. Stray bullets - some were occasionally not so stray - pounded the American positions and American onlookers, some of whom came from as far as Bisbee to see the fighting. Naco, Arizona sustained heavy damages as a result of the continued shelling. “From their trenches and rifle pits, the men of the 10th and their comrades from the 9th Cavalry watched the fighting. It was a dangerous business; the Buffalo Soldier regiment [10th Cavalry] had eight men wounded while the Ninth ‘had some killed and wounded.’ They also lost a number of horses and mules from gunfire straying across the border.” Unlike the previous battles in Sonora, in which Maytorena consistently defeated the Constitutionalist opposition, Naco did not turn into a rout. In fierce combat General Benjamin Hill dug in along the border and supplied his troops from the American side. “Three lines of formidable trenches and earthen breastworks interspaced about 200 yards apart were thrown up around the entire perimeter to the border. Barbed wire and whatever other obstacles could be found were erected to impede the expected attack…the town [of Naco, Sonora] was transformed into a virtual fortress…”
The American troops were under orders not to return fire. As the siege dragged on, the restraint of the U.S. army turned into admirable acts of self-discipline. Colonel William C. Brown of the 10th Cavalry confided in a letter to a friend in October of 1914,
About 12:25 a.m., on the 17th [Maytorena] made the most determined attack yet made [sic]---first from the west, then from the east and lastly from the south, the direction which would send the high shots into our camp and of which he had previously been warned. On the night of the 10th four shots hit the little R.R. station where I had my headquarters; on the night of the 16th-17th, 14 shots hit the same building and I should say that the shots (probably several hundred) dropped in our camp in about the same proportion. Fortunately nearly all men and animals had been moved out for safety but notwithstanding this our casualty list was as follows: Four troopers wounded, one will probably die, and another lose his eye-sight [sic]. One horse and one mule killed one horse wounded besides at least two natives shot on the U.S. side of the line. It is a surprise here that the U.S. takes no notice of such an outrageous proceeding. Does the U.S. Government propose to sit complacently by and allow such deliberate firing perpendicular to the boundary that our soldiers are shot in their own camps? This after repeated warnings of the effect of such firing. If this be true I am having my eyes opened, and getting an entirely new idea of the protection afforded by the U.S. flag.
On December 11, General Tasker H. Bliss inspected the situation in Naco. According to the New York Times, Mexican rebels took potshots at the American general. “…Two bullets fired from the Mexican side of the boundary passed perilously near the General and his staff as he was examining a bomb-proof [shelter] near the immigration station, about 100 feet north of the international line. Soldiers guarding the immigration station are protected by three bomb proofs and by a line of loaded coal cars drawn before the American town and the border, but a break in the line of coal cars had been left to permit access to the border. Gen. Bliss was near this break when the bullets whistled.” Whether Mexican snipers targeted General Bliss on purpose or the incident was accidental, the Wilson administration’s decision to dispatch a larger military force was affirmed. The next day, the U.S. military moved heavy artillery from Fort Bliss, Texas into Naco.
On December 15, the entire 6th Brigade, with 4,750 soldiers headed from Galveston, Texas to Naco, bringing the total American troop strength there to 6,215 men. The American army had assembled a full invasion force, larger and with more firepower than the troops dispatched to Veracruz in April, complete with cavalry, infantry, and heavy artillery. With the blessing of the War Department General Bliss issued an ultimatum on December 16: “If for any reason a single shot falls on American soil after this ultimatum has reached you and has been translated, I will be forced to use extreme measures to end this useless danger to innocent lives in a neutral and well-intentioned country.”
Villa as Commander-in-Chief of the Convention government not only rejected the ultimatum but also, to the alarm of President Wilson and his cabinet, proceeded to give U.S. Army Chief of Staff General Hugh Lenox Scott a taste of old fashioned Mexican machismo. He answered through Felix Sommerfeld: “I have mobilized eight thousand cavalrymen and they left yesterday under the command of General Cabral who will be in Casas Grandes within two days and they will proceed to Naco immediately period…if he [Scott] will permit us the time of eight hours Naco will be taken and the situation will be concluded…the assault will be rapid, uniform and effective period. Please cause General Scott to know this and ask him to have patience for four days…” While Villa’s chest thumping might appear just to be that, the situation could not have grown tenser. Villa threatened war! Moving eight thousand troops to northern Sonora, which was almost completely in the hands of his forces, clearly aimed at the American army, assembled on the other side of the line. The combined forces of Maytorena and Villa numbering approximately 9,500 would trump the assembled American army units.
General Scott took Villa’s threat at face value and cabled to the Secretary of War Lindlay M. Garrison for permission to “…stop movement of Villa’s troops in this direction before leaving the railroad or failing this that all Americans be brought out of Mexico and General Bliss be instructed to protect the town of Naco by repelling the attack by force of arms. General Bliss desires that he receive his instructions in time to bring field hospital from San Antonio and make other necessary dispositions.” As between six and seven thousand American troops readied themselves for a military expedition into Mexico, Villa assembled two full cavalry brigades to assault the border town of Naco. Acting Secretary of War Breckenridge approved the field hospital to be moved in place on January 2, 1915. On January 9, Sommerfeld, who had the ungrateful task of shuttling between Villa and Maytorena, received the long awaited signature from the Sonoran strongman, in which he agreed to give up the siege. Already on the previous day General Hill had left Naco by train for Galveston, Texas to join up with Carrancista forces fighting in Veracruz. The situation was diffused. For now. Within a year the border erupted in violence again, causing virtually the entire regular U.S. army to be stationed in defense of the homeland.