BETWEEN THE years 1846 to 1848, the United States and Mexico went to war.
The two-year-long battle was sparked in part by the Untied States annexation of Texas, which was a Republic at the time but which Mexico still considered to be their own territory.
The war ended with the United States winning Texas, as well as what is now known as New Mexico, California, Colorado, Nevada, Utah and Wyoming, but throughout the war Mexican forces had received help from an unusual source.
The Saint Patrick's Battalion, later known as the Foreign Legion of Patricios, contained around 200 people, most of whom were Irish Catholics who had immigrated to the US and defected to the Mexican side.
The battalion was led by Connemara-born John Riley, who initially fought in the British Army before moving to America, like millions of others in Ireland at the time whose homeland was being ravaged by the Great Hunger.
While most of those involved in the Saint Patrick's Battalion were Irish Catholic immigrants, the legion also contained immigrants from Germany, Canada, England, France, Italy, Poland and Mexico-- many of whom were themselves Catholic.
Others involved in the legion were US citizens who had become disillusioned with America, and even included slaves who had escaped from the US Southern States
The Mexican government considered the Saint Patrick's Battalion to be a great asset to their army, and often sent propaganda in multiple languages across the border to the US in order to enlist more defectors, promising a higher wage than the US Army and acres of land to those who joined them.
The United States also saw the Foreign Legion of Patricios as a threat, with Ulysses S Grant-- who would go on to serve as the 18th President of the United States, and who himself had Irish roots-- stating battles fought against the Battalion were often the "severest".
While Mexico lost the war, and with it large swathes of territories, the actions of the Irish immigrants in the Saint Patrick's Battalion have not been forgotten.
Former President of Mexico Vicente Fox Quesada paid tribute to the Patricios in the early 2000's stating "The affinities between Ireland and Mexico go back to the first years of our nation, when our country fought to preserve its national sovereignty..."
"Then, a brave group of Irish soldiers … in a heroic gesture, decided to fight against the foreign ground invasion.”
The Saint Patrick's Battalion are remembered with pride in Mexico, but the men who had switched sides and fought against the United States were punished harshly, with many being publicly hanged as traitors.
But the Battalion's legacy in Mexico is an honourable one; tributes to the estimated 200 people who fought with them between 1846 - 1848 can be found throughout the country, including a bust of Comandante John Riley which sits in the Plaza San Jacinto in Mexico city.
And in his hometown of Clifden, Connemara, John Riley is honoured with a bronze sculpture in the town square-- a gift from the Mexican government.