They probabaly don't have this celebration in Boston

USA Today:

Every month, a wail of bagpipes reverberates through a plaza in downtown Mexico City, causing startled passersby to stop and stare.

Then, from behind the bullet-scarred walls of an old fortress, a platoon of Mexican bagpipers emerges through the gates — paying tribute to an obscure but divisive chapter of history involving Mexico, Ireland and the United States.

The ceremony honors the St. Patrick Battalion, a group of 600 Irish-American soldiers who switched sides to fight for Mexico in the 1846-1848 Mexican-American War. On St. Patrick's Day, many Mexicans will raise a glass to commemorate the "Irish martyrs" who are regarded as heroes in a war that still arouses passions here.

"It's a little bit of a weird twist on history … and quite romantic for the Irish community," said Myles Doherty, the Irish consul in Mexico City.

The battalion's story begins with Ireland's Potato Famine of the 1840s, which forced thousands of Irish to emigrate to the USA and other countries.

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The deserters became known as the San Patricios and were led by John Riley, an artilleryman who had fought in the British army. They were joined by a few Swiss, French, Scottish and German recruits, most of them also Catholic.

Called los colorados, or "the redheads," by their Mexican comrades, they fought against the Americans at the key battles of Monterrey, Buena Vista and Cerro Gordo.

The Americans eventually reached the outskirts of Mexico City on Aug. 20, 1847. Mexican forces, with the remaining San Patricios handling the artillery, pounded the Americans from a monastery-turned-fort on the Churubusco River until they ran out of ammunition. Thirty-five San Patricios died in the battle, 85 were captured, and another 85 retreated with the remnants of the Mexican army.

On Sept. 13, 1847, the Americans seized Chapultepec Castle in the war's last major battle. San Patricios who had deserted before the war were branded by the Americans with the letter "D" on one cheek. The rest were hanged, including 30 who were executed at the foot of Chapultepec Hill.

"They were hanged at the moment that the American flag was raised over the castle of Chapultepec, so that they would take that sight to hell with them," Mayer said.

Mexico lost nearly half its territory as a result of the war, while the United States gained California and the Southwest. Even today, many Mexican school textbooks portray the war as an unjust land grab by the United States that led to the divergent economic paths followed by the two neighbors.

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It sounds like their sectarian loyalties were stronger than any loyalty to their new country.

It was clearly a mistake for the Mexicans to try to refight the Texas Revolution after Texas became part of the US. It cost them dearly, but not so dearly that many of its citizens would still rather be citizens of the US, no matter what tune or instrument is played.

The divergent economic paths were not caused by the outcome of the war. Mexico is still crippled by economic corruption and state control of resources. If it can institute the rule of law and capitalism it can be a prosperous country. If it did, it would not have so many of its citizens heading north.