Harney Re-Examined, Part IV: William Harney and the Hanging of the San Patricio Brigade

Fourth in San Juan Island National Historical Park's series on General William Harney, commander of U.S. forces during the Pig War.

On the morning of September 13, 1847, William Harney watched American troops storm Chapultepec Castle, the last major fortress guarding Mexico City. At 9:30 a.m. the U.S. flag rose over it — his signal that the battle was won and that it was time to execute his prisoners. Harney ordered the mule carts forward, and the nooses tightened on 30 men. It was the last of three mass executions General Winfield Scott had ordered of the San Patricio (Saint Patrick's) Brigade, mostly Irish immigrants who had fought for Mexico.

A painting of the hanging of the San Patricio Brigade; Harney is presumably the rider in the foreground.

A divisive war

The Mexican-American War split the country. Some Northerners, among them Congressman Abraham Lincoln, called the invasion "from beginning to end, the sheerest deception," because it was unprovoked and unjustified. Lincoln argued — and most historians agree — that President Polk sent the Army into disputed territory hoping Mexican soldiers would fire on it; once they did, Congress gave Polk a blank check for the invasion he had long wanted.

Many Americans saw the war as part of a "Slave Power Conspiracy." Most Americans lived in free states and many opposed slavery, yet slaveholders dominated the federal government, and its laws and policies favoured them. On that view, the war was a scheme to seize Mexican land for new slave states — as some San Patricios had already seen happen in Texas, taken from Mexico by slaveholding Americans a decade earlier.

Who the San Patricios were

• Irish immigrants opposed to the war, many of them U.S. soldiers who resented how abusive officers like Harney treated enlisted men. Some had survived the Irish Potato Famine, watching friends and family starve under British policies that favoured Protestant settlers over the Catholic majority. In the U.S. Army many met anti-Catholic bigotry and brutal discipline; to men from an occupied country, the invasion of Mexico recalled Britain's hold on Ireland.
• Escaped slaves and free Black men, who saw Mexico — which had abolished slavery — as freer than the United States, and fought against slavery's spread.
• Catholic immigrants from Germany, Poland, France and elsewhere, resentful of anti-Catholic discrimination in the United States, which only grew as the largely Protestant country prepared to fight a Catholic one.
• Men drawn by the generous land grants Mexico offered foreigners who enlisted.

In battle

The brigade first fought as its own artillery unit on September 21, 1846, defeating American forces in three engagements at the Battle of Monterrey. The victory drew more American deserters, and the brigade grew from about 200 men to 700. It adopted its battle flag: green, with a gold harp in the centre, shamrocks and the words "Erin Go Bragh."

It became one of Mexico's most capable units. At Buena Vista it took heavy losses, and official reports called its men "worthy of the most consummate praise because the men fought with daring bravery." Despite supply shortages and heavy casualties it fought on until August 20, 1847, at the Battle of Churubusco: when outnumbered Mexican units raised a white flag, the San Patricios fired on them, refusing to give up while any hope remained. In the end, 80 of them surrendered.

Trial and execution

The Army tried them as deserters in two mass trials, tightly managed by General Scott and held just 3 and 6 days after their capture, with no lawyers for the accused and no transcript. Fifty men were sentenced to death and executed as U.S. forces took Mexico City.

Harney's hanging on September 13 was the most brutal. "I was ordered to have them hanged and have no orders to unhang them," he said, and left the 30 bodies to rot on the gallows as a warning to anyone in Mexico City who might resist. Resistance continued anyway: militias and guerrillas fought the occupation until the Treaty of Guadalupe Hidalgo was signed on February 2, 1848. Mexico recognized Texas as part of the United States and gave up part or all of what became California, Colorado, New Mexico, Utah, Arizona, Nevada and Wyoming.

Harney and Scott

As the conquered lands were absorbed, commanders including Harney violently took Native American homelands for white settlers. Harney left Mexico just six weeks after the executions; Scott stayed for months, saw the cost of guerrilla war, and came to value diplomacy in settling hard international disputes. The two men who had carried out the San Patricio executions together later clashed over the Pig War, Harney pressing for aggressive action against Britain and Scott choosing to negotiate.

Remembered

The San Patricios are national heroes in Mexico and Ireland. A plaque honours them in Mexico City's San Jacinto Plaza, where Mexican bagpipers play a monthly tribute. In Clifden, Ireland, birthplace of the brigade's commander, a statue honours them and the town flies the Mexican flag every September 12. In 1997, Mexico and Ireland issued identical stamps bearing both nations' flags. The U.S. Army, which had executed them to discourage desertion, denied the brigade had existed until 1915, when a congressional inquiry exposed the cover-up.

Sources

• National Park Service, San Juan Island National Historical Park, "Harney Re-Examined Part IV: Harney and the Hanging of the San Patricio Brigade," in the series Harney Re-Examined: A New Look at a Forgotten Figure. https://www.nps.gov/articles/000/harney-re-examined-part-iv-harney-and-the-hanging-of-the-san-patricio-brigade.htm
• Part III: https://www.nps.gov/articles/000/harney-re-examined-part-iii-harney-and-the-pig-war.htm
• Corrected: the page spells the battles "Monterey" and "Churubasco"; they are Monterrey and Churubusco.