KENNEBUNK — The early morning St. Patrick’s Day plunge into Portland’s icy harbor, sponsored by Rí Rá Irish Pub, echoes the tradition begun in New York City in 1762, when the first parade honoring Ireland’s patron saint was held by Irish soldiers serving in the British army.

In New York City, the “Fighting Irish” 69th Infantry Regiment leads off its 168th St. Patrick’s Day Parade with two shaggy Irish wolfhounds strutting up Fifth Avenue. This Irish brigade, organized by Irish revolutionary and Civil War Union Gen. Thomas Meagher from County Waterford, was invited in 1851 to lead the St. Patrick’s parade to protect the Irish from violence orchestrated by anti-immigrant “Know-Nothings.”

After Benjamin Franklin visited Ireland in 1762 and witnessed the wretched conditions in which the Irish lived under British rule, he wrote his fellow patriots in Massachusetts: “All Ireland is strongly in favor of the American cause. They have reason to sympathize with us.”

Although “Ireland occupied an ambiguous place in Americans’ thoughts about global politics,” according to historian David Sim, American independence would not have been achieved without the Irish.

When the shot heard ’round the world was fired, 147 Irishmen were among the Minutemen at Lexington and Concord. After the smoke cleared April 19, 1775, 22 Irishmen would have given their lives in America’s initial bid for independence.

Gen. George Washington proclaimed March 17 a day of rest for his Continental Army in 1780, acknowledging the cause of Irish freedom and the Irish-American alliance against the British Empire. Americans were not going to allow themselves to be ruled as Ireland was. Forty-five percent of Washington’s Army was Irish.

In the Siege of Yorktown sequence of Lin-Manuel Miranda’s hit musical, Alexander Hamilton asks: “How did we know that this plan would work? We had a spy on the inside. That’s right!”

The chorus shouts: “Hercules Mulligan!”

Mulligan, Irish-born tailor and agent of the patriots’ spy network, replies: “A tailor spyin’ on the British government! I take their measurements, information and then I smuggle it to my brother’s revolutionary covenant. I’m runnin’ with the Sons of Liberty and I am lovin’ it!”

The morning after the British evacuated New York City, Nov. 26, 1783, George Washington invited Mulligan to breakfast. The city was returned to the victorious patriots and declared the capitol of the United States.

Washington wrote an Irish friend Jan. 20, 1784: “It is with unfeigned satisfaction I accept your Congratulations on the late happy & glorious Revolution. … If in the course of our successful contest, any good consequences have resulted to the oppressed Kingdom of Ireland, it will afford a real source of felicitation to all who respect the interests of humanity.”

Lord Mountjoy lamented in Parliament on April 2, 1784: “America was lost by Irish emigrants … . I am assured from the best authority, the major part of the American Army was composed of Irish and that the Irish language was as commonly spoken in the American ranks as English. I am also informed it was their valor that determined the contest.”

After Cornwallis surrendered at Yorktown on Oct. 19, 1781, at the surrender ceremonies, the British regimental band played the familiar march, “The World Turn’d Upside Down.” The Irish in the Continental Army accelerated the pace of that downward turn.

The Irish, skilled at verbal arts, raised a glass to their dual identity at the centennial celebration of Boston’s Charitable Irish Society, on March 17, 1837: “To Ireland and America. May the former soon be as free as the latter, and may the latter never forget that Irishmen were instrumental in securing the liberty they now enjoy.”

Irish participation in the American Revolution helped give birth to a new nation. The Irish-Americans returned the favor after the 1916 Easter rising, when “Ireland … supported by her exiled children in America … strikes in full confidence of victory.” Ireland’s war of independence ended with the Anglo-Irish Peace Treaty in 1921 and “Ireland, long a province, A Nation once again!”

Erin go Bragh! America forever!