1. On September 1, 1864, the Battle of Fort Stevens took place in Washington, D.C. during the American Civil War. Confederate forces, led by General Jubal Early, made a daring attempt to capture the capital city but were ultimately repelled by Union troops.

2. September 1, 1939 marked the beginning of World War II, when Germany invaded Poland. This event had a significant impact on the District of Columbia, as the city became a major hub for the war effort and home to numerous military installations.

3. In 1969, the Washington Metropolitan Area Transit Authority (WMATA) was established on September 1. The agency is responsible for operating and expanding the city's public transportation system, including the iconic metro system.

4. September 1, 1971 saw the opening of the Kennedy Center for the Performing Arts, a world-renowned venue for music, theater, and dance. The center was named after President John F. Kennedy, who had championed the arts during his administration.

5. On September 1, 2004, the District of Columbia became the first jurisdiction in the United States to legally recognize same-sex marriages performed in other states. This landmark decision paved the way for marriage equality nationwide.