1. On April 4, 1865, Union troops captured the city of Salisbury during the Civil War. The capture of Salisbury was seen as a major victory for the Union Army and helped to weaken the Confederate forces in Maryland.

2. On April 4, 1951, the Johns Hopkins University School of Medicine became the first medical school in Maryland to admit women. Prior to this, women were not allowed to attend medical school in the state.

3. On April 4, 1968, the day after the assassination of Martin Luther King Jr., riots broke out in Baltimore. The riots lasted for several days and left six people dead and over 700 injured. It was one of the most destructive riots in Baltimore's history.

4. On April 4, 1999, the Baltimore Orioles played their first game at Oriole Park at Camden Yards for the 1999 season. The Orioles defeated the Tampa Bay Devil Rays 9-6 in 11 innings.

5. On April 4, 2015, the Maryland men's basketball team won the National Invitation Tournament (NIT) championship, defeating the Stanford Cardinal 59-53. It was the first time since 1972 that the Maryland men's basketball team had won a post-season tournament.