Though Curt Flood made $90,000, a very good baseball salary in 1969, money wasn’t everything. When the St. Louis Cardinals tried to trade him to Philadelphia, he said “no,” even though all major-league baseball contracts included a “reserve clause” that bound players to their teams even after the expiration of their contracts.

“A well-paid slave is nonetheless a slave,’’ Flood told sportscaster Howard Cosell after the outfielder sued Major League Baseball in a historic challenge to the reserve system, which had been in place since at least the 1880s.

Flood, then 31, had been with the Cardinals 12 years, and if the team no longer wanted him, he wanted to have the right to have others bid for his services. The owners thought that would cause a financial calamity.

“That’s the great fallacy,’’ former deputy commissioner Steve Greenberg said, “that baseball could not survive free agency.’’

Cardinals general manager Bing Devine traded Flood, Tim McCarver, Byron Browne and Joe Hoerner to the Phillies for Dick Allen, Cookie Rojas and Jerry Johnson.

“Bing was operating in the system that was there,’’ said Barry Horn, Devine’s son-in-law. “He didn’t begrudge anybody anything.’’

On Dec. 14, 1969, Flood sent a letter to baseball commissioner Bowie Kuhn, writing in part, “I do not feel I am a piece of property to be bought and sold irrespective of my wishes.’’

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Flood essentially asked to be declared a free agent — a term not known to baseball. Kuhn denied the request, and Flood’s one-man opposition to the reserve clause ignited a battle that ended in June 1972 with the Supreme Court allowing the clause to stand.

By that time, Flood, a three-time All-Star and seven-time Gold Glove outfielder, was out of baseball. He died at 59 in 1997, leaving his wife, actress Judy Pace; five children and two stepdaughters. Pace, 73, declined to comment for this story.

“I lost money, coaching jobs, a shot at the Hall of Fame,’’ Flood was quoted after the Supreme Court decision. “But when you weigh that against all the things that are really and truly important, things that are deep inside you, then I think I’ve succeeded.”

A decision spawning free agency arrived late in 1975 when MLB arbitrator Peter Seitz ruled in favor of cases brought by pitchers Andy Messersmith and Dave McNally. While Seitz reportedly said Flood’s suit did not directly impact his decision, MLB historian John Thorn said: “There is not a straight line legally; however, there is a straight line emotionally. Pyrrhic victories don’t hold up well in history books, right? But Curt Flood had won. He stood up for principle.”

Flood stood alone against baseball.

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“He got no support, no help,’’ said Allan Zerman, Flood’s longtime attorney in St. Louis. “In private, some people would pat him on the back and say, ‘You’re out of your mind. You’ve given up your career, you’ve given up all this money.’ He had some cheerleaders, but they never came forward. They were never present. He said he understood why they wouldn’t jeopardize their careers, but deep down, there’s no question in my mind he was disappointed and hurt.’’

Zerman recalled Flood’s reaction to the Supreme Court decision, saying: “He was crushed, disappointed, although it was not totally unexpected. What he couldn’t know at the time was he really had won.’’

McCarver, 74, who once considered himself a close friend of Flood’s, recently said: “If there’s anybody with a more courageous legacy in the game, I don’t know who it is. During that time, everybody was talking about the selfish Curt Flood. He was anything but selfish. It was proven to be as legitimate a stance as anyone could make on any particular issue, and yet he was by himself. We were questioned in those days, ‘Would you do it?’ Nobody could afford to do it.”

After the ’69 season. McCarver and former Cardinals teammate Dal Maxvill were on a flight with Flood to Puerto Rico for a meeting of the Players Association. Flood was going to ask for financial help in his $1-million suit against Kuhn and MLB.

“On that flight, I said, ‘Why in the world are you doing this?’ ” Maxvill, 76, said recently. “He said, ‘I just feel like I got to do this.’ I said, ‘You know this will not have a good ending.’ He said, ‘I still have to try it.’ Nobody had ever thought about doing this. He had the guts to do it.’’

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There were pointed questions to Flood from the players. According to author Brad Snyder, who wrote “A Well-Paid Slave,’’ Dodgers catcher Tom Haller “point-blank asked is this a black power thing? Curt said, ‘No, it’s about a human thing, being able to choose who you want to work for.’ ’’

Zerman said that while Flood championed civil rights issues, race never entered his suit against baseball.

Flood gained the financial support of the union, but even strident Players Association executive director Marvin Miller reportedly told him the suit would not succeed.

Flood was supported by Hall of Famers Jackie Robinson and Hank Greenberg, Steve’s father.

“I think he’s kind of a sad case,’’ Steve Greenberg said of Flood. “He was a great player who was a bit of a martyr in a sense. His career was colored by the stand he took. He didn’t feel like he wanted to be treated like chattel and he felt like that’s what the system was doing to him and he took a stand.’’

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Maxvill said: “As far as other players saying, ‘If I get traded, I’m not going,’ that never happened. I don’t know that the players today fully appreciate the sacrifice he made for them.’’

Union spokesman Greg Bouris wrote in an email that the “Players Association has made it a priority to educate active players about the union’s history and the sacrifices — individual and collective — of previous generations of players to leave the game better for those who follow. Of course, Curt’s heroic legacy is part of this history.”

Flood sat out the entire 1970 season while his suit went through litigation. Before the Supreme Court decision, Flood was signed by Washington Senators owner Bob Short to a $110,000 contract to play in 1971. Flood lasted only 13 games.

“He said I just can’t hit anymore,’’ former Senators first baseman Frank Howard, 79, said recently.

Flood’s teammates still did not understand his suit. “We were so used to being with one ballclub and never dreamed that free agency would come into play,’’ Howard said. “He blazed the trail and set the trend for what’s happening in professional sports today. The money these young men are making, it’s all because of him.”

McCarver encountered Flood in 1994 at the White House, where Ken Burns’ documentary “Baseball’’ was being premiered. “It was not a warm meeting, I’m sorry to say,’’ McCarver said. “Because nobody really supported him. It was as cordial as it could be, but it wasn’t cordial.’’

Flood did express solidarity for the players in August 1994 when he addressed them before the strike that ultimately canceled the World Series.

Last summer, the Hall of Fame commemorated Flood on the 45th anniversary of his sitting out the 1970 season.

“I think Curt is getting posthumously what he should have gotten when he was alive,’’ McCarver said. “That’s small solace, I suppose. But nonetheless, he is getting it. I suppose better to get posthumously than not at all. I certainly wish he had gotten the acclaim he deserved when he was living.’’