CLEVELAND — Two fan bases conditioned to expect the worst from their baseball teams over the last century were put through one emotional wringer after another Wednesday night in an epic Game 7 of the World Series.

In a deciding game that featured just about everything — appropriate for franchises that had not won a title in a combined 174 years — the Cubs finally prevailed, 8-7, in a 10-inning classic in front of 38,104 at Progressive Field, winning their first World Series since 1908.

In ending the longest title drought in professional sports, the Cubs, whose complete top-to-bottom roster helped them win an MLB-best 103 games in the regular season, finished off a rally from 3-1 down in the Series.

After the Cubs scored twice in the top of the 10th, the Indians scored once in the bottom half, with Cubs manager Joe Maddon bringing on lefty Mike Montgomery to face Michael Martinez, inserted for defense the previous inning.

Montgomery got Martinez to ground to third to finally, at long last, secure the title.

The Cubs became the first team to trail 3-1 in a series and win since the 1985 Royals (over the Cardinals) and the first two do so having to win the last two games on the road since the Pirates in 1979 (over the Orioles).

The Cubs happily bequeathed the “longest-without-a-World-Series” crown to the Indians, who have not won since 1948.

Still, their sizable contingent of fans that filled up nearly half the stadium — or at least sounded like that many — were forced to pay quite an emotional toll on their way to ecstasy.

The Cubs, playing in their first World Series since 1945, built a 5-1 lead in the fifth inning and held a 6-3 lead with four outs to go before all heck broke loose in the eighth.

There, Rajai Davis hit a two-run homer to cap a three-run eighth against a gassed Aroldis Chapman, tying it at 6.

The game went into extras but not before a brief rain storm caused a 17-minute delay.

After the tarp was removed, Kyle Schwarber started the 10th with a single against righty Bryan Shaw and was replaced by pinch runner Albert Almora, who went to second on Kris Bryant’s long fly out to center. Anthony Rizzo was intentionally walked and Ben Zobrist, hot all series, came through by hitting a 1-and-2 pitch to left to bring in Almora to make it 7-6. Miguel Montero’s RBI single made it 8-6.

Right-hander Carl Edwards Jr. got the first two outs of the 10th before Brandon Guyer, who doubled in a run before Davis’ eighth-inning homer, walked with two outs, giving Davis one more crack. Davis singled to bring in Guyer to make it 8-7.

The Cubs and their fans had all but counting down the outs since the middle innings as lefty Jon Lester, who started and won Game 5, picked up for Kyle Hendricks, the left-hander protecting what seemed a comfortable 6-3 lead in the eighth.

The improbable started to become possible for the Indians with two outs when Jose Ramirez reached on an infield single.

Cubs manager Joe Maddon brought on Chapman, who threw a career-long 22/3 innings in Game 5 and, somewhat controversially, was brought on in the seventh inning of Game 6 with a five-run lead. Guyer greeted Chapman with a double, which brought in Ramirez.

Davis, who committed two mistakes in center earlier in the night that contributed to two Chicago runs, then lined a 2-and-2, 97-mph fastball just over the wall in left, the two-run homer shaking Progressive Field and tying it at 6.

The Cubs put a runner on third with one out in the ninth but Javier Baez attempted to bunt with two strikes — he did not succeed — and Cleveland shortstop Francisco Lindor ranged toward second to stop a Dexter Fowler grounder back up the middle, throwing the leadoff man out by a step.

Lost a bit in the thrilling final innings was Chicago finally solving Cleveland ace Corey Kluber and star reliever Andrew Miller.

Kluber, 4-1 with a 0.89 ERA in five previous starts this postseason but seeing the Cubs for the third time in nine days, allowed four runs and six hits over four-plus innings. Miller, who came in having allowed one run in 17 postseason innings, allowed two over 21/3 innings Wednesday night.

The Indians inserted some drama in the bottom of the fifth after the Cubs had taken a 5-1 lead in the top half on a Baez homer off Kluber and off Rizzo’s RBI double off Miller. Carlos Santana walked with two outs and Maddon brought in Lester to face Jason Kipnis. The second baseman hit a dribbler to the right side of the mound and reached first, going to second on a wild throw by David Ross, Lester’s personal catcher who entered along with the pitcher.

With Francisco Lindor at the plate, Lester buried a breaking ball in the dirt that skipped off Ross’ mask and rolled all the way to the Cubs dugout. That allowed Santana and Kipnis to score, bringing Cleveland within 5-3.

But the Cubs, as they did each time the Indians scored in the game, seized back momentum. The 39-year-old Ross, playing in his final game, hit a towering home run to center with one out in the sixth, making it 6-3.