The integration of the Cardinals was a complicated story. First, the Cards' owner from 1947-1953, Fred Saigh, was opposed to signing any black players. When he pled guilty to tax evasion, he was forced to sell the team to August "Gussy" Busch Jr. Busch is credited as saying "Wow can it be the great American game, if we don't have any negro players? We've got to get colored ballplayers." That sentiment was less progressive than it was pragmatic. He followed that up with "Hell, we sell beer to everyone."
The rest of the story is a tale of two players, Tom Alston and Len Tucker. In 1953 the Cardinals signed Len Tucker as their first black player. Tucker was an all around college athlete at Fresno State. He was a track star, he led the Basketball team in points per game and led the baseball team in homers and RBIs. Despite performing well in the Cardinals minor league system but never got promoted to the bigs.
Instead the Cardinals went with a more proven player. They purchased Tom Alston from the San Diego Padres of the Pacific League. They immediately experienced buyer's remorse. Alston was two years older than they had thought and asked for $20,000 of the $100k they spent on him to be returned.
Alston was hitless in his first seven at-bats, but his first two MLB hits were both over the fence. By mid-May he was batting over .300 with 4 homers. After that, he cooled off quite a bit. By the end of June he had the same 4 homers and an average of .246. He spent the rest of the season in the minors. He played in just 25 more MLB games over the next three seasons.