 Most Irish-Americans had settled in the northern, American states and were thus called up to serve when the southern states seceded and formed the Confederacy in 1861.Many Irish-Americans on both sides formed their own units which embraced Irish customs such as Catholic masses and priests.On March 3, 1863, Congress passed the Enrollment Act which required single men age 20 to 45 and married men up to age 35 to register for the draft.