sentences:  The Packers are also the only team to win three straight NFL titles, which they did twice (1929–1931 and 1965–67).After going through modest winning seasons during most of the 1920s, the Packers began to build a championship-caliber team, as they signed three future Hall of Famers in "Johnny Blood" McNally, Cal Hubbard, and Mike Michalske.The Packers won their first NFL Championship in 1929 with a 12-0-1 record, the only undefeated season in Packers history.