If you're finding it difficult to watch postseason baseball with the Red Sox on the sidelines after a disastrous season, we invite you to take a moment to reflect on one of the first great moments in Boston baseball history — the first World Series and the unlikely song that helped the home team win the day.

By 1903, America’s love of baseball had blossomed into a full-blown affair.

"It’s really the only pastime that we had," said Roger Abrams, Richardson Professor of Law at Northeastern and author of "The First World Series and the Fanatics of 1903." "It would be another 20 years before the National Football League. Basketball had just recently been invented in Springfield so there’s no basketball. Anyone playing hockey was north of the border, so baseball was it."

At the turn of the century, there were a myriad of baseball leagues, all fighting for players, and the hearts — and dollars — of growing legions of fans.

"By 1903, they had settled the economic war between the American League and the National League, which resulted in the creation of the Major Leagues," Abrams said.

One thing the new major leagues didn’t have was an official postseason championship. As the 1903 season neared it’s end, it was clear that the Pittsburgh Pirates would be champions of the National League and that the Boston Americans would take the pennant for the upstart American league. That’s when Pittsburgh owner Barney Dreyfuss wrote a letter to Boston owner Henry Killilea.

"[Killilea] said, 'We can have a World Series,' and he used the words 'World Series' — kind of presumptuous to call it a world series — but indeed he was right that people wanted more baseball," Abrams said.

So a best of nine games series was arranged. And on Oct. 1, 1903 at 3 p.m. Boston’s Cy Young threw the first pitch of the first World Series from the mound at the Huntington Avenue Baseball Grounds.

"The Huntington Avenue Grounds were enormous," Abrams said. "Centerfield was 500 feet away from home plate, and so they filled the outfield with patrons. Many of them sat up on the high walls looking like pigeons on the deck of a ship. Eighteen thousand people came out for that first game."

… to watch the home team lose. Days later, the team boarded a train to Pittsburgh down two games to one.

"And in addition, on this train was a group that became famous in Boston and that was the Royal Rooters," Abrams said.

The Rooters were a gang of a few hundred Boston baseball fanatics that included future Boston mayor — and John F. Kennedy grandfather — John “Honey Fitz” Fitzgerald. Their leader was a gruff, impish, mustachioed saloon owner named Michael “Nuff Ced” McGreevy.

"The reason why he was called “Nuf Ced,” is that that’s how he resolved disputes in his bar, Abrams said. "McGreevy would get up there and say, 'Ahhh, 'nough said.' And the dispute was settled."

The Rooters were known for their fierce dedication to raucous musical cheering from the stands. With their team facing long odds in Pittsburgh, the Rooters hatched a plan.

"Nuff Ced had two of his lieutenants go down and find some new music, ‘Maybe we need some new music,’" Abrams said.

What they turned up, was a Broadway tune of the day, called “Tessie.”

"The Royal Rooters would sing the song, and they would sing it over and over again to the point where, all of a sudden, Boston was winning, and won game after game," Abrams said.

The team — and the Rooters — returned to Boston for Game 8, up four games to three, and …

"… with the strains of Tessie wafting over the South End, Boston was victorious," Abrams said.

Baseball’s first World Series championship belonged to Boston.

The Boston Americans would officially change their name to the Red Sox after the 1907 season, and of course go on to win seven more World Series championships, the most recent last year.

“Tessie” would get dusted off and updated by the Dropkick Murphy’s in 2004, and once again become a rallying cry for the team that year, as they broke the “Curse of the Bambino” and won their first World Series in 86 years.

And as momentous an occasion as that first World Series was for baseball, Abrams says it was also a pretty important moment for the growing — and changing — City on a Hill.

"There were the fancy folks from Beacon Hill, there were the Irish, probably second generation, immigrants right off the ship, every newspaper in Boston had story upon story," he said. "I can’t think of any other event where you would get such a collection of different kinds of Americans, and they met in a common purpose. I find that kind of fascinating."

Baseball’s first modern World Series, won by the home team. And it got underway, right here in Boston, 111 years ago this week.

"Tessie," by The Dropkick Murphys: