National Museum of American History
One of the best museums in DC, a grand tour of American history, from transportation to pop culture, everything that defines what American life is and was.
The exhibits relating to military themes usually show what it was like in domestically and how American involvement in the world reflected on itself domestically.
It showcases where Americans can be proud of their history but does not shy away from the events where America did not live up to its ideals. Both are critical in understanding the United States.
link to their website – National Museum of American History