Washington, D.C. is a major city and the former capital of the United States. It was destroyed during the Invasion of Earth. It was succeeded as capital of the U.S by Charleston, South Carolina. Serving as the location of the final battle with the Espheni, the city was eventually reclaimed by humanity.
Cochise informs the 2nd Mass which areas his recon team are unable to access, which includes the entirety of Washington D.C.
Following the destruction of the Espheni Power Station and a failed attempt to destroy the 2nd Mass, Tom Mason rallies all the militias and the Volm in the United States for a march on Washington, D.C. where the Espheni forces are retreating to and where the Espheni have apparently begun to establish their base of operations. Using the Shadow Plane, Ben Mason learns that the Espheni Queen has arrived to Earth and is based in D.C. and Dornia supply Tom Mason with a weapon to use on her to defeat the Espheni. Using information from the Shadow Plane, the 2nd Mass figure out that their target is the Lincoln Memorial as all the Espheni are gathering there with their queen. After discovering that the Espheni have erected a powerful defensive wall around the city, the plan is changed so that all of the other militias attack the wall as a diversion while a strike team and the Volm, led by Tom Mason, uses the city's service tunnels to reach the queen and kill her, rather than an all-out assault on the Lincoln Memorial. Heavy fighting erupts as dozens of Mason militias assault Washington D.C. and attempt to bring down the Espheni wall surrounding the city, apparently resulting in a confrontation with a number of skitterized humans. In a confrontation at the Memorial with the queen, Tom uses the Dornia bioweapon on the Espheni queen, killing her as the Dornia virus enters her system. Through her biological link to the entire Espheni race and their forces, the virus destroys the entirety of the Espheni race and their forces, including their biological servants and Earth is reclaimed. Several months later, humanity gathers in a reclaimed Washington, D.C. to elect a new leader and listen to a speech by Tom Mason.