1. In 1790, the Residence Act was signed into law by President George Washington, establishing Washington, D.C. as the capital of the United States. Prior to this, the capital was located in New York City.

2. In 1863, during the Civil War, the Battle of Manassas Gap took place in Warren County. Union forces led by Brigadier General George A. Custer clashed with Confederate troops in a series of skirmishes over control of the Shenandoah Valley.

3. In 1917, the Washington Senators defeated the Detroit Tigers in a 10-inning game at Griffith Stadium. The game was notable for the performance of pitcher Walter Johnson, who struck out 18 batters and allowed only one run in the victory.

4. In 1969, astronaut Neil Armstrong became the first person to set foot on the moon as part of the Apollo 11 mission. Armstrong famously declared, "That's one small step for man, one giant leap for mankind," as he stepped off the lunar module onto the moon's surface.

5. In 1990, Washington, D.C. Mayor Marion Barry was arrested on drug charges in a sting operation at the Vista International Hotel. The incident garnered national attention and led to a trial that exposed the mayor's long-standing struggles with drug addiction.