Early in the morning of April 12, 1861, Confederate shore batteries opened fire on Fort Sumter, the federal fort in Charleston Harbor. Northerners and Southerners immediately recognized that the Civil War had begun. Governor John Andrew of Massachusetts, a prominent Republican and a staunch supporter of Abraham Lincoln, anticipating such a possibility, had brought the various militia units up to peak performance. As soon as the President issued his proclamation on April 15, calling for "the militia of the several States of the Union" to suppress the rebellion, the Bay State's response was both speedy and efficient.

Governor Andrew called upon four Massachusetts regiments to report to active duty, and the next day the 8th Regiment marched into Boston. The following morning, the 6th Regiment arrived in the city, and together the two regiments made their way to the State House to receive their regimental colors from Governor Andrew before marching off to the aid of an isolated Washington.

With the attack on Fort Sumter, the Irish Catholics of Boston flew to the colors at once, declaring that they were prepared to give their lives for the preservation of the Union. The Pilot, the Catholic weekly, assured the city that "the Irish adopted citizens are true, to a man, to the Constitution,'' and promised that they would fight to preserve the Union. "We have hoisted the American Stars and Stripes over the PILOT Establishment," wrote the editor, "and there they shall wave till the 'star of peace' returns."

While a number of Boston Irishmen joined up with local militia groups, there were many who wanted an Irish regiment of their own. Thomas Cass, former commander of the Columban Artillery, an early Irish militia unit that had been forced to disband during the Know-Nothing hysteria of the mid-1850s, now offered his services to organize a regiment of Irishmen. With Governor Andrew's enthusiastic permission, Cass was assigned the rank of colonel, and used the nucleus of the old Columban Artillery to begin recruiting for the 9th Regiment Massachusetts Volunteer Infantry. A recruiting station on Sudbury Street formed companies of men from the Boston area, which were augmented by other companies of Irishmen from Salem, Milford, Marlborough, and Stoughton.

A month-long schedule of basic training for the new Irish regiment was held at a camp on Long Island. Equipped with new .69 caliber muskets, the recruits engaged in company drills, guard mountings, and dress parades under the strict supervision of Colonel Cass. On Tuesday, June 25, one month after their arrival, the Irish troops returned to Boston to receive their regimental colors. Escorted by marching bands and cheering crowds who lined both sides of the streets, they made their way from Long Wharf, along State Street, to the State House. Standing at attention, the troops watched as Governor Andrew, followed by his staff, walked down the steps bearing a flag with the Bay State emblem that he presented to Colonel Cass in honor of "this splendid regiment."

The governor also presented the regiment with a green silk Irish flag. On one side were the words: "Thy Sons by Adoption; Thy Firm Supporters and Defenders from Duty, Affection, and Choice." In the center of the banner was the American coat of arms, eagle and shield. Beneath this, in gold letters, was inscribed: ''Presented to Colonel Thomas Cass, Ninth Regiment Massachusetts Irish Volunteers." On the reverse side of the banner was the Irish harp, surmounted by 34 stars, and surrounded by a wreath of shamrocks. After formal military review on Boston Common that followed the ceremonies at the State House, the 9th Regiment -- the "Fighting Ninth" as it came to be known -- hoisted their banners and marched out of Boston, headed for the bloody battlefields that lay ahead.

More than satisfied with the success of the 9th Regiment, Governor Andrew asked President Lincoln's permission to raise additional units -- including another Irish regiment. Late in September, the governor informed Patrick Donahoe, editor of The Pilot, that he could begin recruiting a second Irish regiment right away. By this time the governor had found that such prominent Irish Catholics as Donahoe, Andrew Carney, a wealthy clothier, and John B. Fitzpatrick, the Bishop of Boston, were among his most loyal and dependable supporters. In July 1861, in fact, Fitzpatrick was informed that the trustees of Harvard College had voted to confer upon him an honorary doctor of divinity degree, "probably the first time [such a degree] was ever bestowed on a Roman Catholic Ecclesiastic at Cambridge," wrote his friend Amos A. Lawrence. While this honor was obviously a genuine gesture of friendship and respect for Fitzpatrick himself, Lawrence wanted the Bishop to know that this would not have happened were it not for "the loyalty shown by him and by the Irish who have offered themselves freely for the army."

But the year 1861 was just the beginning. For the next four years, Irish regiments would become an integral part of the Union Army as it moved forward to defeat the Confederate forces and restore the Union. Only a decade earlier, the Know-Nothing legislature of Massachusetts had labeled Irish Catholics as a lawless, dangerous, and violent people, and had promised to eliminate all traces of "Rome, Rum, and Robbery." Now, in the face of a major national crisis, these same Irish Catholics would be praised for their gallantry and courage in defense of the Constitution of the United States.

Thomas H. O'Connor is a professor emeritus and the university historian at Boston College.