1. On September 15, 1862, the Battle of Harper's Ferry took place during the American Civil War. The Union forces, led by General McClellan, captured over 11,000 Confederate soldiers and disrupted General Lee's plan to invade Maryland.

2. The Washington Monument, one of the most iconic landmarks in the city, was completed on September 15, 1884. The 555-foot tall obelisk took over 36 years to construct and honors the first President of the United States, George Washington.

3. The National Museum of the American Indian opened its doors to the public on September 15, 2004. The museum, located on the National Mall, features exhibits and artifacts that highlight the history and cultures of Native American tribes throughout North, Central, and South America.

4. On September 15, 1977, President Jimmy Carter signed a treaty, known as the Panama Canal Treaty, that transferred ownership and control of the Panama Canal from the United States to Panama.

5. The Washington Redskins, now known as the Washington Football Team, played their first regular-season game on September 15, 1935, against the New York Giants. The Redskins won 13-3 in front of over 27,000 fans at the Polo Grounds in New York City.