Pancho Villa attacks Columbus, New Mexico

On March 9, 1916, Mexican General Francisco "Pancho" Villa invaded the US (18 killed). From the article:

"Pancho Villa attacks Columbus, New Mexico
Angered over American support of his rivals for the control of Mexico, the peasant-born revolutionary leader Pancho Villa attacks the border town of Columbus, New Mexico.

In 1913, a bloody civil war in Mexico brought the ruthless general Victoriano Huerta to power. American President Woodrow Wilson despised the new regime, referring to it as a “government of butchers,” and provided active military support to a challenger, Venustiano Carranza. Unfortunately, when Carranza won power in 1914, he also proved a disappointment and Wilson supported yet another rebel leader, Pancho Villa.

A wily, peasant-born leader, Villa joined with Emiliano Zapata to keep the spirit of rebellion alive in Mexico and harass the Carranza government. A year later, though, Wilson decided Carranza had made enough steps towards democratic reform to merit official American support, and the president abandoned Villa. Outraged, Villa turned against the United States. In January 1916, he kidnapped 18 Americans from a Mexican train and slaughtered them. A few weeks later, on this day in 1916, Villa led an army of about 1,500 guerillas across the border to stage a brutal raid against the small American town of Columbus, New Mexico. Villa and his men killed 19 people and left the town in flames.

Now determined to destroy the rebel he had once supported, Wilson ordered General John Pershing to lead 6,000 American troops into Mexico and capture Villa. Reluctantly, Carranza agreed to allow the U.S. to invade Mexican territory. For nearly two years, Pershing and his soldiers chased the elusive Villa on horseback, in automobiles, and with airplanes. The American troops had several bloody skirmishes with the rebels, but Pershing was never able to find and engage Villa.

Finally losing patience with the American military presence in his nation, Carranza withdrew permission for the occupation. Pershing returned home in early 1917, and three months later left for Europe as the head of the American Expeditionary Force of World War I. Though Pershing never captured Villa, his efforts did convince Villa never again to attack American citizens or territory. After helping remove Carranza from power in 1920, Villa agreed to retire from politics. His enemies assassinated him in 1923. The resentment engendered in Mexico by the efforts against PanchoVilla, however, did not fade with his death, and Mexican-American relations remained strained for decades to come."