When did Irish begin to emigrate?

There were three groups. One came before the American revolution in the 1600's and the second/ third came in the 1860's and the late 1880's. Many young Irish men were signed up for the civil war as they came off of ships .
There were three groups. One came before the American revolution in the 1600's and the second/ third came in the 1860's and the late 1880's. Many young Irish men were signed up for the civil war as they came off of ships .