On this day in 1935, player/manager Charlie Grimm took the "player" label off his business card. He had gone hitless in spring training and followed that up by going hitless in his first 8 at bats during the season, and decided that was enough. He handed the first base job to Phil Cavarretta so Grimm could concentrate on managing.
As a player, Charlie was a slick fielding first baseman and steady hitter. As a manager, he seemed to have a magic touch. In 1935, he led them to one of their most magical seasons of all time. That was the year the Cubs won 21 games in a row at the end of the season to win the pennant.
Grimm continued to manage the team until the middle of the 1938 season, when he was kicked up to the radio booth.
He returned to manage the Cubs two more times, including their last pennant winning season of 1945. In his first ten seasons as Cubs manager, the team won the pennant three times, finished in second place twice, and in third place four times. That's probably why Charlie is widely considered to be the second best Cubs manager of the 20th century (behind only Frank Chance).