This Day in Baseball June 18 - 4 over 400
ThisDayinBaseball.com has tons of June 18 action like this:
2002 - In the first major league game to feature four players with 400 career homers, the Cubs beat the Rangers, 4-3, when Alex Gonzalez hits a walk-off homer in the bottom of the ninth inning. Sammy Sosa (475), Fred McGriff (459), and Juan Gonzalez (401) watched Rafael Palmeiro add his 460th home run to the total.