Portland’s Michael C. Connolly, professor of history at St. Joseph’s College, delivers again with a fact-packed but thoroughly entertaining history of the city’s Irish longshoremen with “Seated the Sea.”

Not only does the book fill in a huge gap in the maritime history of Portland, the East Coast and the nation, but it deals directly with the hot-button issue of race dating back to the early 19th century.

Diversity did not always engender good fellowship. Indeed, Gaelic-speaking newcomers (and the port had the highest concentration of Irish speakers in the nation) found themselves in a hostile environment.

The search for jobs in the United States pitted these non- or poor-English speakers against the lowest-paid Yankee laborers and, in Portland, black workers on the wharfs. Willing to work for less and sticking together, ultimately forming a union (which changed over time), the Hibernians pushed the blacks off the docks into service on the steamboats.

Connolly has written about this before in “Black Fades to Green” (Colby Quarterly, 2001), but here it is presented fully nuanced. In many ways, it was a numbers game. In the port of New Orleans, with many African Americans, the work was split 50-50 between black and white longshoremen.

But this is getting ahead of things. I am giving a pass on the title “Seated the Sea” from Longfellow’s most overused poem, because cargo handlers do work along the shore and because the poet was born in a house later used by longshoremen families, including the father of Gov. Joseph E. Brennan, who contributed the introduction. Connolly, too, comes from such a hardworking clan, and his thesis on the union was written at Boston University in 1988.

Local politicians, fishermen, real-estate developers and anyone active in the working harbor should look lively here and glance back, because in telling the story of the longshoremen and their Irish heritage, Connolly hits on many of the root causes of the port’s success and failures to meets its potential at key times in history.

He has gone back to Robert Babcock and all the best sources, and he has shown what the port was and has become — really a shadow of its former self.

Against the backdrop of statistics are the influences of the Catholic church, whose bishops were interested in the fate of the working man and his family but often opposed to outside or nationally organized unions. The church saw such “brotherhoods” as secret societies, dangerous and a direct challenge to its authority.

The appearances of Italians on the waterfront led to renewed ethnic tensions, this time Catholic vs. Catholic and the eventual creation of the Italian Freight Handlers Union. The late Rev. Joseph Romani once told me that “In the old days, if you wanted to call someone something bad, you called him an Irishman.” It was an ethnically divided waterfront until after World War II when, as longshoreman Roy Caleb noted, “Italians and Irish here intermingled and intermarried.”

Certainly one of the volume’s strengths is the interviews with old-timers. Tom Mulkern notes, “There wasn’t that much crookedness around. We always had better (working) conditions than they had in Boston ’cause we made them. We sat around the table and we made those conditions.”

It was not all smiles and sunshine, however — there were strikes, violence and eventually arguments about national affiliation. Current dockworkers in the Portland Longshoreman’s Benevolent Association number a mere handful compared to the boom days of the early 20th century.

In the end, Connolly asks what the future of the working waterfront is. Will it be simply a rich man’s playground, as longshoreman Larry Welch saw it, or something better suited to its unique geography?

“Seated the Sea” is a well-documented revelation and a challenge for this generation. 

William David Barry is a local historian who has authored or co-authored five books, including “Tate House: Crown of the Maine Mast Trade” and the novel “Pyrrhus Venture.” He lives in Portland.