from Mark Ross at athlonsports.com
1. On April 15, 1947, Jackie Robinson, 28, played first base for the Brooklyn Dodgers, becoming the first African American to play in MLB’s modern era in the process. By breaking the color barrier, Robinson forever changed America’s pastime...
2. Similar to Jackie Robinson, Frank Robinson was a trailblazer in his own right. A Hall of Fame player with 586 career home runs, two MVP awards and a Triple Crown, Robinson debuted as player-manager of the Cleveland Indians back on April 8, 1975, becoming the first African American manager in major league history.
3. Twelve U.S. presidents have thrown out the ceremonial first pitch of the MLB season. The first to do so was William Howard Taft back on April 14, 1910.
4. It was known as "The House That Ruth Built" and if there was every any doubt as to why, just go back to what happened on April 18, 1923. On the first Opening Day in Yankee Stadium (the original, not the one that opened in 2009), Ruth fittingly produced the first home run-- a three-run shot into the right field bleachers.
5. On April 4, 1974, Hank Aaron forever etched his name into the record books when he hit a three-run home run off of Cincinnati's Jack Billingham in the top of the first inning at Riverfront Stadium. Besides staking his Atlanta Braves to an early 3-0 lead, it represented the 714th home run in Aaron’s career, tying Babe Ruth for the most in MLB history.
6. Hall of Fame pitcher Bob Feller threw three no-hitters in his career, including one on April 16, 1940.
7. On April 13, 1926, the Washington Senators and Philadelphia A’s opened their season by needing 15 innings to decide the winner. While on the surface that may not seem that impressive, consider that the two starting pitchers-- Walter Johnson and Eddie Rommel-- were on the mound for the entire game!
8. Toronto's George Bell hit three home runs off of Kansas City starter Bret Saberhagen on April 4, 1988 to become the first player to do so in his team's opener.
9. Those in attendance at Progressive Field on April 5, 2012 got to see plenty of baseball action. The Cleveland Indians and Toronto Blue Jays battled for 16 innings, the longest Opening Day game in MLB history.
10. In 1901, the Detroit Tigers, playing their first-ever game, trailed the Milwaukee Brewers 13-4 headed into the bottom of the ninth. The home team mounted a monumental rally, tallying 10 runs to beat the Brewers, 14-13. More than 110 years later it remains the greatest Opening Day rally in major league history.
The details can be read here.