Hundreds with the "Million Vet March" protest the closure of the memorials during the federal government shutdown at the world war 2 memorial.
The protesters removed the barriers and entered the memorial, which has been closed since the shutdown began October 1.
Some protesters carried barricades to the White House and rallied outside the gates, confronting police in riot gear.
President Obama said Thursday that national parks could reopen as long as each state paid the operation costs.
Colorado, Utah and Arizona all took advantage. The future of the nation's capital's parks, however, is unclear.