Boston was a dominant team in the new league, defeating the Pittsburgh Pirates in the first World Series in 1903 and winning four more championships by 1918. However, they then went into one of the longest championship droughts in baseball history, called by some the "Curse of the Bambino" after its alleged beginning with the Red Sox's sale of Babe Ruth to the rival Yankees in 1918, an 86-year wait before the team's sixth World Championship in 2004.