August 18, 1952. My Dad took me to see the Cubs play the Pirates. The Pirates scored single runs in the 2nd, 4th and 6th innings. The Cubs finally scored in the 8th when Hank Sauer hit a sacrifice fly. The Cubs entered the bottom of the 9th down by 2 runs. Bill Serena walked. Johnny Edwards (a catcher) pinch hit and hit a triple into the right field corner. Now the tying run was on 3rd with no outs. Phil Cavaretta, the player-manager, put himself into the game and hit a walk-off HR.
Attendance that day was a whopping 4,911. The victory brought the Cubs up to a .500 record. They had been 15 games over .500 in mid-June. They finished the year in 5th place at .500--the last time that would happen for a while.
Sauer would win the NL MVP that year. It was Cavaretta's last home run as a Cub. After the 1953 season (65-89), he told the press that the Cubs were unlikely to finish above 5th place in the 1954 season. As a result, owner Phil Wrigley fired him.
I cannot find a reference to this, but I think Cavaretta may be the all-time leader for most hits prior to age 20.