1. The Irish immigrants were ill-treated in the US army where they were seen as different; some authors claim that they were not allowed to practice their Catholic religion.
2. The Mexican government offered them incentives such as land if they switched sides.
3. The Irishmen were uncomfortable with the US army’s treatment of the Mexican population.
Portrait by Benjamin D. Maxham (daguerreotype), black and white of Henry David Thoreau in June 1856.
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The Flag Book of the United States by Whitney Smith; Page 272 John Patrick O'Reilly
‘In memory of Seán Ó Raghailligh, a native of Connemara; Irish soldier; the original ‘San Patricio.’ Hero of the war of 1847. A man who chose to defend those whom he could have attacked and vanquished. The place and year of his death are still not agreed upon.”
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