The club honored emergency first responders of all stripes, including police, firefighters and emergency medical technicians. The "We Shall Never Forget" logo, which baseball debuted in September 2001, was displayed on the field behind home plate.
Among those recognized on the field during the ceremony were St. Louis County police chief Col. Tim Fitch, St. Louis City police chief Col. Daniel Isom and St. Louis Fire Department Chief Dennis Jenkerson.
For many in attendance, though, the most resonant moment came before any of those people took the field. The Cardinals showed a video of the late Jack Buck reading his poem, "For America," which he first read at the previous Busch Stadium prior to the Cardinals' first game back on the field after the attacks.
"It is important that baseball and our country remember what happened on [this] day," said Braves manager Fredi Gonzalez. "There are days during the baseball season that bring real emotion. Fourth of July, Labor Day, Memorial Day. Now, this is one of those days."
For an honorary first pitch, the Cardinals had St. Louisan Angela Brock-Bokern, who survived the attack on the World Trade Center. She threw to Albert Pujols, the only Cardinals player who was also on the team in 2001.
Players on both sides were fully cognizant of the magnitude of Sunday's events.
"I flew out of Newark Sept. 10 after the  season ended," said Cardinals infielder Skip Schumaker. "There's a lot of emotion. I'm sure everybody has a story, they knew somebody or something. This day is about more than just a game. This is completely different than [singer] 'El Torito' throwing out a first pitch. This is a historic day that affected everybody in America."
Braves pitcher Tim Hudson was with Oakland in 2001 as a young Major Leaguer. On Sunday, he was the Braves' starter.
"It was a time that changed this country forever," Hudson said. "None of us will ever forget those involved. They are still our heroes."
As part of their commemoration, the Cardinals issued free game tickets to approximately 5,500 emergency first responders in the area. The St. Louis City First Responders Color Guard presented the nation's colors.
And then, of course, the clubs had to get back to work.
"You're going to be rightfully distracted by the significance of what it was, then you have to turn that button back to compete," said Cardinals manager Tony La Russa. "But it's the same for both teams. But it's not anything that happens easily. You have to make a point to put everything in its place."
Matthew Leach is a reporter for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.