Years ago, as a young historian searching for an as yet untold story on which to write my doctoral dissertation, I came across some obscure reference about Irish famine immigrants to New Orleans. Predestined, I think, by my last name and a much-loved grandfather from Co Roscommon, I was intrigued by this footnote, and, after some investigation of the local universities, I bought a plane ticket to America’s most exotic city. I had never been there before and had an image in my head of ferocious hurricanes, alligator-infested swamps; legendary pirates; sultry Dixie jazz; elegant Creoles; mysterious voodoo; French and Spanish customs, and exquisite food all mixed together into a savoury cultural gumbo.

Where exactly the Irish fit in was really not so clear to me.

So I turned to the cabdriver, always a reliable source for fledgling historians, and asked him if he knew anything about Irish in New Orleans. I will never forget his reply. “Goil,” he said in this inimitable accent that, as I would soon learn, characterises the Irish New Orleanian, “we Irish’s everywhere in dis cidy,” and proceeded to give me an account of New Orleans Irish history, peppered with darling, sweetheart and other terms of endearment that usually no strange man would use towards a woman – except in Ireland. If my cabdriver was to be believed, I had hit pay dirt.

And, indeed, he had not embellished. Over the next quarter of a century, my life was filled – and it still is – with uncovering and teaching the history of the Irish in New Orleans. It is a story rich in adventure, human drama and sacrifice, compassion, great triumphs and celebrations. It is, in short, a testimony to a significant people.

The Irish were part of New Orleans’ history from the start. Records dating back to the colonial period already list Irish names. There were Murphys, McCarthys and O’Malleys here, although often with curiously un-Irish first names like Jean or Miguel or Santiago. These hardy fellows were merchant adventurers on the make or soldiers of fortune who had left Ireland during the eighteenth century to escape the increasingly oppressive penal laws and joined the militaries of Catholic France and Spain to protect the crowns’ far-flung dominions.

One of the more colourful ones serving the Spanish king was a military genius named Alejandro O’Reilly, who had been sent to the young colony of Nueva Orleans to restore order after the town’s residents had forcefully ejected the Spanish governor. O’Reilly and his Spanish and Irish-born troops entered the city with a bang – literally – and the pragmatic Irishman proceeded to quell the rebellion by hanging the leaders of the obstreperous citizenry and distributing their property to his Irish merchant friends who just happened to be along for the trip. Blessed with such good luck, several of them decided to stay, marry into local Creole families and create vast fortunes and legacies that resonate in New Orleans to this day.

Decades later, New Orleans, among the few Catholic cities in North America, became a port of call for refugees from the failed rebellion of 1798. As a port city with a vibrant, internationally connected economy, New Orleans was rich in opportunity and free from British oppression. And there were also a number of well established Irish in town who could offer welcome and help.

How early an Irish community became an identifiable presence (as far as the strict guidelines of historians are concerned) is evidenced by the first newspaper report of a St. Patrick’s Day parade on March 17th, 1806. I take no small measure of pride in the fact that I discovered the authentic account of the 17 “official” toasts that were pronounced at this momentous occasion. Clearly, the city’s already well-established reputation for enthusiastic imbibement and the ancient Irish traditions surrounding this Saint’s feast day had found common ground.

The nascent Irish community prospered in the booming economy following the Louisiana Purchase in 1803, as the port of New Orleans grew into the fourth largest port in the world. The Irish’s own magnificent St Patrick’s Church was built in 1833. By the mid-1850s, the Irish controlled the ocean-to-river vessel transport and were firmly embedded in every line of the city’s business and trade. In fact, New Orleans is home to the first public monument in the United States to honor a woman – the life-size statue of the great 19th century entrepreneur and philanthropist, Margaret Haughery, an illiterate, widowed immigrant from County Leitrim and life-long resident of the city. The Irish Tiger roared!

Annually, thousands of ocean-going vessels docked, sometimes eight deep, along the wharfs. Moving cargo from their holds onto steamboats to be distributed throughout the newly enlarged nation was a logistical enterprise of immense proportion. Vast resources, financial and human, were needed to keep this global economic hub humming. The Irish community continued to grow as word got back to Ireland that life was good in New Orleans.

It is an unfortunate truth that the growth of the Irish diaspora has come at great cost to the mother country, then and now. Like many other places around the globe, New Orleans, too, experienced a vast inflow of Irish Famine refugees. The passage from Liverpool to New Orleans cost as much as a ticket to New York; and, unlike the latter, New Orleans imposed no quarantine. Moreover, the region’s economy was booming at an unprecedented rate. King Cotton ruled. Jobs were aplenty and prosperity was hard work’s reward.

The Irish families of New Orleans opened their arms to these tens of thousands of Famine refugees, and together they built the foundations of the Irish New Orleans community that thrives to this day. In the decade preceding the Civil War, when the Irish made up over a quarter of the city’s population, this community, consisting to a large proportion of individuals and families who had to sell their possession to escape from the famine-ravaged home land, miraculously built five spectacular churches, as well as orphanages and parochial schools to serve its needs.

Today, the Irish New Orleans community is just as vibrant and energetic as it was over 150 years ago. We bow with pride to the old Irish families who have lived here since the early beginnings, and we continue to welcome new arrivals. We have Irish dance schools, Irish music, theatre and film festivals, a Gaelic football league, dozens of Irish pubs and restaurants, our St. Patrick’s Day toasts have vastly exceeded their modest origin and in 2012, the state legislature formally declared the month of March to be Louisiana’s official Irish month.

There are many more stories in my book, The Irish in New Orleans, and I have many more that are still to be put to paper. But in addition to the personal stories I have uncovered, I have also found a common identity that to this day connects the diaspora with its land of origin. In a larger sense, this book exemplifies an expansion of Irish national identity beyond the traditional geographical boundaries, one inclusive of its diaspora. Faced with the challenges of a global economy, the combined energies of old Ireland and its diaspora are bound to be as successful now as they were in the past.

The Irish in New Orleans is published by University of Louisiana at Lafayette Press

Jimmy Deenihan, Minister for the Diaspora, launches it at the Irish Whiskey Museum, Dublin, at 6.30pm on June 10th.

Laura D Kelley teaches history at Tulane University, New Orleans