Former Rep. Ronald V. Dellums, a Marine-turned-antiwar activist who represented Oakland in the House and went on to chair the Armed Services Committee, died of cancer early Monday in Washington. He was 82.

Known for championing progressive social movements before they became popular, his career in politics spanned over 40 years, 27 of them in Congress and four as mayor of Oakland.

“I feel blessed to have called Congressman Dellums my dear friend, predecessor, and mentor. I will miss him tremendously, and I will hold dear to my heart the many lessons I learned from this great public servant,” Rep. Barbara Lee said in a statement. The California Democrat succeeded Dellums in the House in 1998. 

House Minority Leader Nancy Pelosi, who represents nearby San Francisco, remembered her former colleague as a “progressive hero and outstanding leader.”

“With his passing, our Bay Area community, the U.S. Congress and all working people have lost a dear friend.  The world is a darker place without the warmth and humanity of this great man,” she said in a statement. 

Dellums’ stance against the Vietnam War earned him a spot on President Richard Nixon’s “Enemies List.” During his first run for Congress in 1970, Vice President Spiro Agnew labeled him “an out and out radical,” according to the San Francisco Chronicle.

“If it’s radical to oppose the insanity and cruelty of the Vietnam War, if it’s radical to oppose racism and sexism and all other forms of oppression, if it’s radical to want to alleviate poverty, hunger, disease, homelessness, and other forms of human misery, then I’m proud to be called a radical,” Dellums told reporters in rebuttal.

After enlisting in the Marine Corps and serving for two years, Dellums returned to the Bay Area to earn a bachelor’s degree in psychology from San Francisco State University, followed by a master’s in social work from University of California, Berkeley.

In 1967, Dellums won a seat on the Berkeley City Council before being elected to Congress three years later to represent the Berkeley and Oakland areas. Running on an antiwar platform, Dellums criticized the Democratic incumbent Jeffery Cohelan for his late opposition to the Vietnam War, and ended up winning the primary, 55 percent to 45 percent.

Dellums quickly drew media attention as a new member of Congress.

Rather than quietly learning the ins and outs of the House, he hit the ground running, introducing more than 200 pieces of legislation.

Championing the anti-establishment sentiment on which he won his seat, Dellums held his own ad hoc hearings for alleged American war crimes in Vietnam after Congress refused to conduct an investigation.

As a founding member of the Congressional Black Caucus, Dellums served as an active voice in the anti-apartheid movement in South Africa. He sponsored numerous bills to end U.S. support of the pro-apartheid South African government. Finally, in 1986, Dellums put forth a bill calling for a U.S. trade embargo against the country and divestment of American companies in the nation. The bill passed via voice vote.

In pursuit of his long-standing goal to cut the military budget, he sought a seat on the House Armed Services Committee during his second term in office. Dellums explained in his book “Lying Down with the Lions” that he sought to mitigate the accusations of his opponents that he was uninformed or naive in his beliefs on strategic defense. 

He quickly rose through the ranks and eventually became chairman surprising many critics with an even-handed approach to such hot-button issues as pay increases for the troops, banning gays from the military and anti-missile funding boosts.

Assigned to the District of Columbia Committee during his first term in office, Dellums first introduced what became one of his major goals: statehood for Washington, D.C.

“There should be no colonies in a democracy, and the District of Columbia continues to be a colony,” he said at a committee hearing in 1987, according to House archives.

Dellums resigned from Congress on Feb. 6, 1998, midway through his 14th term. In his farewell speech, he reflected on his work in the House.

“To get up every day and put on your uniform and put on your tie and march on the floor of Congress knowing that, in your hands, in that card, in your very being, you have life and death in your hands, it is an incredible thing,” he said.

After Congress, Dellums worked as a lobbyist until being elected mayor of Oakland in 2006 at age 70. During his tenure, he brought the police force of Oakland up to a record high and hauled in more federal stimulus money than any other city, according to the San Francisco Chronicle.

He later drew criticism for being absent from City Hall and for his police force boost becoming unsustainable — in 2010, Oakland laid off 80 officers, according to the Chronicle. That year he announced he would not seek re-election.

Dellums was married three times and is survived by five children. One son, Michael, remains in prison on conviction of a drug-related homicide in 1979. Another son, Erik, is a professional actor, known for his roles on the Baltimore-set television drams “Homicide: Life on the Street” and “The Wire.” Daughter Piper Dellums is an author.