After years of parallel coexistence, the American League and the National League agreed in 1903 to pit their respective champions against one another in a best-of-nine World Series to determine global supremacy.
The Pittsburgh Pirates, led by Hall of Famers Honus Wagner and player-manager Fred Clarke took their third NL title in four years by going 91-49-1, six and a half games ahead of the New York Giants. The Boston Americans, meanwhile, rode the arms of 20-game winners Cy Young, Bill Dinneen and Tom Hughes to pace the AL with a record of 91-47-3, fourteen and a half games ahead of the Philadelphia Athletics.
The series started on October 1, with the Pirates taking two of three in Boston to take the lead before the action headed to Allegheny (where the Pirates actually played), where they also won Game 4 to take a commanding 3-1 lead. But the Americans peeled off three straight road wins to go up 4 games to 3 with the series heading back to Boston.
Game 8, on October 13, 1903, pitted the Pirates' Deacon Phillippe against the Americans' Bill Dinneen. Phillippe had been among the NL's best pitchers that season, finishing in the top ten in wins, ERA and strikeouts, but in the World Series he'd ben asked to carry an unusually heavy load--even by the standards of the time--due to his teammate Sam Leever having injured his shoulder in a skeet shooting contest. Leever started Game 2, but pulled himself after just one inning, as his team lost 3-0, then he went the distance in Game 6, with the Pirates again losing, 6-3.
Phillippe to this point had gone the distance on October 1, 3, 6, and 10, winning the first three and losing the fourth. Now he was again taking the bump, this time with the season on the the line. Dinneen for his part, had pitched "only" three games thus far, going the distance in each with a record of 2-1.
Dinneen retired the first eleven batters in a row, before finding himself with men on first and third and two outs in the fourth with Kitty Bransfield at the plate, but he got out of the spot unscathed when Tommy Leach was gunned down at home on the front end of a double steal. The Americans' Buck Freeman led off the bottom of the fourth with a triple, eventually coming around to score on Hobe Ferris' two-run single to center. Ferris would come through again in the sixth with another RBI single to center, while Dinneen continued to set down the Pirates hitters.
In the ninth inning, Dinneen got Clarke to fly out to left, Leach flied out to center and Wagner struck out, making the Boston Americans baseball's first World Series champions.
The World Series MVP Award wasn't yet a thing, but had it been, it almost certainly would've been awarded to Dinneen, who went 3-1 with a 2.06 ERA across 35 innings. Not bad for a guy who the year before had led the American League with 21 losses.
Dinneen would make his final appearance as a big league pitcher on August 26, 1909, and less than three weeks later embark on a long and distinguished career as an umpire, calling an AL-best eight World Series, as well as the first All-Star Game, reliever Ernie Shore's "perfect" game, and the game the Detroit Tigers lost 24-2 when the starters staged a one-game walkout to protest Ty Cobb's suspension and the Tigers were forced to field a team of coaches and college players who were at the game.