Most of these boys would have been of English and Scottish Protestant background and not very friendly to Catholics. This is not to be taken as a harsh criticism of these soldiers. But from the time they were small they received a great deal of anti-Catholic information. This was all they knew. At the same time the blight on the Irish potato had occurred and now the Irish nation was suffering from the famine.
Large numbers begin to emigrate to the United States.
Many of them were recruited into the army. They participated in the American advance into Mexico. Meanwhile, they were suffering the taunts, mockery and discrimination of their fellow soldiers. As the army made progress and occupied village after village in Mexico, the Irish troops saw the little churches and observed the strong Catholic faith of the native population. They began to question what they themselves were doing.