1. In 1865, President Abraham Lincoln died after being shot the previous evening by actor John Wilkes Booth at Ford's Theatre in Washington, D.C. April 15 is now recognized as the day of Lincoln's assassination.

2. In 1912, the Titanic sank after hitting an iceberg on its maiden voyage. The disaster resulted in the deaths of more than 1,500 people. At the time, the news of the tragedy took some time to reach Washington, but it had a profound impact on the city.

3. In 1947, Jackie Robinson broke the color barrier in Major League Baseball when he made his debut for the Brooklyn Dodgers. Robinson had been signed by Dodgers executive Branch Rickey, who wanted to integrate the game. Robinson faced intense racism and discrimination throughout his career, but he became one of the greatest players in MLB history.

4. In 1981, the first Space Shuttle launch took place when Columbia took off from the Kennedy Space Center in Florida. The mission was a test flight and lasted two days. Despite the success of the launch, the Space Shuttle program would face several setbacks and tragedies, including the loss of Challenger in 1986 and Columbia in 2003.

5. In 2013, two bombs exploded near the finish line of the Boston Marathon, killing three people and injuring more than 260 others. The attack was carried out by two brothers, Tamerlan and Dzhokhar Tsarnaev. Tamerlan was killed in a shootout with police, while Dzhokhar was captured and later sentenced to death. The Boston Marathon bombing was one of the deadliest terrorist attacks on American soil since September 11, 2001.