The Mexicans call them "the Irish martyrs" of the war of 1847 when the United States invaded Mexico and took almost half its territory. They are commemorated in a suburb of Mexico city where 50 were hanged, 48 of them Irish, and others flogged and branded with red-hot irons on their faces with a "D".
For the conquering Americans, the Irish of the San Patricio battalion were deserters who deserved their brutal fate. Mexicans, however, see them as heroes who gave their lives defending their adopted country against an unjustified invasion which still rankles south of the Rio Grande.
Tomorrow, for the first time, a President of Mexico and a Mexican foreign minister will attend the annual ceremony in San Jacinto Square, where 16 of the Irish were hanged. A plaque gives 71 names of the members of the San Patricio battalion led by Captain John O'Reilly from Co Galway. As the names are read out, the Mexicans present will respond: "Died for Mexico".
President Zedillo will lay a wreath. The foreign minister, Angel Gurria, will speak, as will the new Irish non-resident ambassador to Mexico, Mr Sean O hUiginn. President Zedillo and An Post will jointly issue a commemorative stamp honouring the Irish soldiers tomorrow. The anniversary will also be commemorated in Clifden, Co Galway. At a museum in Mexico city devoted to the "invasions" endured by Mexico since the Spanish con- quistadores, there are souvenirs of the Irish because many died at that spot - defending the 17thcentury monastery which is now beautifully preserved as the museum - in the battle of Churubusco, a vain attempt to stop the US troops entering the capital.
The quiet square in front of the building is called Plaza Batallon San Patricio in honour of the Irishmen who died in battle. There are also commemorations in other Mexican cities where the Irish fought against the invading Americans.
How the Irish changed sides and then paid dearly is a little known saga in Ireland, but Mexico still cherishes the memory. For Americans, the "Mexican War of 1847", let alone the role of the Irish, is scarcely remembered today.
How the war started is still regarded as controversial. The Mexicans see it as a naked landgrab by their powerful northern neighbour which coveted not just Texas but California and the territories today known as New Mexico and Arizona. This huge area, now part of the US, was once part of the Spanish Empire: it had passed to Mexico when it threw off Spanish rule in 1821.
The hostilities broke out in the disputed territory of Texas in 1846, following a skirmish between Mexican cavalry and US soldiers. This gave President Polk the excuse he needed to declare war because the Mexicans had "shed American blood on American soil".
Even Abraham Lincoln, then a young Congressman, and Ulysses S. Grant, the future Civil War victorious commander and US President, believed that the invasion of Mexico was not justified.
This was a period when the large immigration of Irish fleeing the Famine was stirring up bigotry among the earlier settlers, and the numerous Irish soldiers in the US army under General Zachary Scott were apparently badly treated by their officers, who added anti-Catholic prejudices to the prevailing anti-Irish feeling. John O'Reilly, who had emigrated from Galway, deserted before war was declared and this was to save his life later. Other Irish soldiers followed him across the Rio Grande to join the Mexican forces soon to be headed by General Santa Anna, the conqueror of the Alamo 10 years earlier.
It is said the Irish were attracted by the Catholic culture of Mexico as well as repelled by the discrimination against them in the US army, but the motives of those who deserted have never been clearly understood given that still larger numbers of Irish soldiers did not do so. As the war progressed, the Irish grouped in the 200-strong San Patricio battalion, under a green banner with St Patrick and the Mexican eagle, distinguished themselves as artillery specialists and inflicted heavy casualties on their former comrades at the battles of Monterey and Buena Vista. But the Mexican forces were being pushed back towards the capital as Santa Anna made a series of tactical blunders.
The US army, now under the command of a tough Virginian, General Winfield Scott (Old Fuss and Feathers), landed at Vera Cruz and marched on the capital. The San Patricios, whose bravery and skill were noted by the Mexican officers, fell back with their allies on Mexico City.
Those who survived the Churubusco battle and were captured were soon court-martialed for desertion. The historian, Michael Hogan, author of The Irish Soldiers Of Mexico, says the punishments inflicted on the Irish went beyond what was allowed by the military code of the day and that the whole episode was denied for years by the US army.
The hangings and brandings were particularly brutal. Thirty of the condemned were forced to wait for hours with the noose around their necks until the final Mexican surrender at Chapultepec Castle.
Mr Hogan says the severity of the punishments indicates that the US army officers were "motivated by causes not articulated by American historians". General Scott in his statement after the executions said they should be a warning to "Catholics and non-Catholics alike" that desertion would not be tolerated. Why did he bring the question of religion into it? Mr Hogan asks.
For years the tragic story of the San Patricios had almost been forgotten, although the Irish-born US ambassador to Mexico, Mr William O'Dwyer, has recorded that in 1950, "the fact that I was of Irish extraction was regarded favourably" because of the memory of the San Patricios.
Patricia Bustamente Cox, an Irish-Mexican woman, researched the episode and wrote a novel about it in the 1950s which has been reprinted many times. Now a film has been made by Mark Day.
There is now little chance that the San Patricios could be forgotten in Mexico or Ireland. But in the US, their decision to change sides will continue to be seen as a matter of shame.
The Irish Soldiers Of Mexico by Michael Hogan is published by Fondo Editorial Universitario
