But out of the carnage came many lessons, and new definitions of what it meant to be part of a country, a city, a team.
Sept. 11 taught the country that sports do matter, that their inherent brotherhood was indeed an American ideal. And so, when New York City was ready stand up, brush off the dust and keep trudging forward, sports became the centerpiece -- the band-aid for a nation.
That's how all eyes came to be trained on Mike Piazza and the Mets some days later, on Sept. 21, 2001. The rest of the country had since done its best to move on, but New York was still iced in shock. And it was up to those Mets to thaw the city, to play New York's first professional game since the tragedy, and bring with that whatever strands of hope and emotion they could.
What they got -- a dramatic Piazza home run that meant more for a city than it ever could for a team -- was an antidote beyond expectation.
The Braves had a 2-1 lead heading into the bottom of the eighth inning. With a man on, Piazza -- already among the most-adored Mets in history -- strode to the plate and drilled a game-winning two-run homer.
And the crowd, for 10 days stunned into silence, came alive.
"As far as drama goes, that was like a Hollywood script," said longtime Mets radio personality Ed Coleman. "You could write it up and people wouldn't believe it."
Tom Glavine was there, too, on the other side with the Braves. And he, like every one of the 41,235 in attendance, was chilled.
"I was kind of getting that feeling of, 'Well, this is one of those nights where maybe there's a higher authority that's watching over this,'" Glavine said. "'Maybe this is happening for a much bigger reason.' You were kind of getting the feeling that you had no control over what was going to go on -- it was meant to be."
The Mets have certainly seen plenty more punishing home runs, and plenty more celebratory ones, too. In 1986, Lenny Dykstra hit arguably the most important home run the Mets had -- and still have -- ever seen, launching a two-out, two-run walk-off to give them a 2-1 win in Game 3 of the National League Championship Series.
Todd Pratt made his mark, too, giving the Mets a 1999 NL Division Series win with his walk-off homer in the 10th inning of Game 4. That one forged its dramatics more out of its novelty -- in 14 years as a big leaguer, Pratt hit just 49 other homers.
And only weeks later, Robin Ventura stamped his name on Mets lore with a walk-off grand slam single. Mobbed by teammates after drilling his homer out of the park in Game 5 of the NLCS, Ventura never officially made it around the bases, stripping the hit of its four-bag status, but not of its significance.
Now, the world has watched again as Barry Bonds tried his hand in the business of memorable home runs. The importance is there, but only time will tell if No. 756 has what it takes to become, in baseball lore, unforgettable.
Time has already tolled for Piazza. No other Mets home run was as memorable as the one that jolted off the catcher's bat in the wake of tragedy.
It meant little to the the postseason hopes of the Mets, who finished that season in third place. It meant little for Piazza, just one of more than 400 in his career. But it meant everything for a team, a city, a nation so desperately trying to heal.
"As a player, you appreciate when great things happen, and as a human being, you have an appreciation for the moment," Glavine said. "The moment was very emotional in obviously everything everybody had gone through. And now to have the Mets' favorite son at the time hit a big home run, I mean, you get chills. You sense the excitement and the emotion for everybody that's at the ballpark that night, and it's hard not to notice that."
Anthony DiComo is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.