One of the landmark moments not for just sports, but for civil rights in America, occurred in 1947 when Brooklyn Dodgers General Manager Branch Rickey signed Jackie Robinson to a contract and made Robinson the first player in the modern era of baseball to break the color line. While there were players of color in the early days of professional baseball, Moses Fleetwood Walker in the 1880’s being one of the most prominent, “The National Pastime” had established hard lines against integration for decades before the Dodgers made their move, and Robinson entered the history books.

The story has been documented in film and print countless times, and is memorialized every year on Jackie Robinson Day by every team in Major League Baseball, one of the most all-encompassing and fitting tributes to a pioneer and a leader and those around him. But what about the other sports and those who took the heat so that others would be able to play?

In the NBA it was Nat “Sweetwater” Clifton, in the NHL it was Willie O’Rhee, and in pro football, a sport whose integration tied to baseball very closely, it was not one but four players, all of whom had an impact on both Rickey and Robinson directly.

Their stories are told this week in a new documentary from Ross Greenburg, “Forgotten Four,” which debuts Tuesday night on EPIX. Greenburg is no stranger to baseball fans, having done countless pieces on the game over the years, with one of the most notable being the heart-wrenching “Nine Innings From Ground Zero” while he was at HBO.

So how does football’s integration impact baseball? Here are a few ties that lay out in the documentary about Woody Strode and Kenny Washington and the LA Rams and Marion Motley and Bill Willis and the Cleveland Browns.

(1) Strode and Washington were teammates of Robinson at UCLA. Before Jackie and brother Mack starred on the baseball diamond they were elite athletes on the gridiron for the Bruins. Strode and Washington were key members of UCLA’s football success, as was Jackie, who helped build the football dynasty in Westwood way before John Wooden created the “Pyramid of Success” at Pauley Pavilion.

(2) Motley and Willis’ success with the Browns in 1946 had a direct impact on having Rickey move forward in ’47 with his Dodgers plan. In the film, Football Hall of Fame historian Joe Horrigan tells a story about Rickey, who also owned the Brooklyn Dodgers football club of the expansion All-America Football Conference. In ’46, The Browns, also in the AAFC before joining the NFL, played at Ebbetts Field against the Dodgers and Rickey was so impressed by the way Paul Brown’s team handled  their African-American teammates that he saw the time was right to integrate baseball. Horrigan recounts Rickey approaching Motley after the Dodgers brought Robinson in and thanking him for showing that integration in pro sports was possible.

(3)The Four actually broke the color barrier the year before the Dodgers grand experiment, although it gets less play until this landmark documentary. Why the four have been forgotten is up for some debate, but football was there the year before baseball.

“I think there were a number of reasons as to why this story isn’t widely known,” Greenburg said. “First in 1947 baseball was the national pastime, football was an afterthought, so Jackie’s move was much more of a headline and at that time had a bigger impact on society. Second, as it says in the film, Robinson did it alone; these four players did it together, so sometimes the impact of one person is seen as bigger than as a group, although that is probably not true as these men endured bigotry and isolation and challenges that were just as big as anything Jackie experienced in baseball. Their story is certainly none less compelling, and it is great that EPIX has given us the chance to tell it now.”

Some critics have said that the football color line is less impactful because the gap from no players until these four came along was really only about 14 years, as players of color, although small in number, did play in pro football in the 1920’s and early ‘30’s until Redskins owner George Preston Marshall pressured other owners to keep blacks out. Baseball’s color barrier was much longer. However it doesn’t change the fact that these four players turned the ride and set the stage in football, like Robinson and then Larry Doby in the AL, did in baseball.

Regardless of semantics, the film is a great view for all fans and will give baseball fans pause when integration is discussed going forward. The Forgotten Four and their ties to Jackie Robinson, now linked forever in video, just like they have been for decades in history.