Prior to Branch Rickey and the Dodgers signing Jackie Robinson they had to lay some groundwork. This included doing some scouting, and in order to disguise their intentions they got involved in the short-lived United States Baseball League.
What's that, you say?
In 1945, legendary and often controversial Negro League pioneer, William A. "Gus" Greenlee, started up the league in order to compete with the much more established Negro National and American Leagues. By this time he had been pushed out of those organizations, and he was looking for an avenue to get back in the game.