After retiring next month, U.S. Park Police Chief Teresa Chambers said, she will relax with her husband in their house in Southern Maryland’s Calvert County, finish half-read books and decorate for Christmas. (2011 photo by Susan Biddle/FOR THE WASHINGTON POST)

U.S. Park Police Chief Teresa C. Chambers, who was ousted from her job in 2003 for criticizing staff shortages and battled for eight years to get reinstated, announced Thursday that she plans to retire Dec. 7.

Recounting her long legal fight, Chambers, 56, said it was important for her to leave the federal agency on her own terms. She decided to exit on anniversary of the day her first police badge was pinned on as a patrol officer on the Prince George’s County force more than 30 years ago.

“There wasn’t a better time to walk out,” Chambers said in an interview Thursday.

Her selection as chief of the Park Police in 2002 made her the first woman to lead the federal law enforcement agency responsible for protecting land controlled by the National Park Service, which covers a wide swath of downtown Washington, including the Mall and the monuments. Officers are also active in New York and San Francisco.

Park Police officers typically get noticed during the protests that frequent the open spaces of the nation’s capital, and they were the lead agency policing last year’s Occupy D.C. movement, making national news when they moved on the protesters.

Most recently, Chambers joined two of the District’s other female law enforcement leaders, the head of Washington’s FBI field office, Valerie Parlave, and the D.C. police chief, Cathy L. Lanier, at the helm of the command center during the Washington Navy Yard shooting rampage that left 12 people dead. A Park Police officer and a D.C. police officer fatally shot the assailant.

Chambers called the experience “humbling to be a part of” but said it showcased how well police from different agencies could work together. She was pleased that people did not seem to dwell on the fact that the three women were in charge of the operation. “One or two people said, ‘Oh, my gosh, look at that,’ ” Chambers said. “Then we got right back to business.” When she started on the Prince George’s force in 1978, she said, “that would’ve been the headline. Now, it’s almost like a footnote. That’s progress.”

Lanier said Chambers had been a “pleasure to work with as a partner in law enforcement.”

Chambers will perhaps be best remembered for being suspended in 2003, and later fired, for telling The Washington Post that she lacked sufficient officers to do her job. She said traffic accidents had increased on the Baltimore-Washington Parkway because only two instead of four officers were patrolling there.

Chambers battled the government for eight years before winning her job back in 2011 and becoming a champion for whistleblowers. She announced her upcoming departure on the Park Police’s Twitter feed, but her statement was written by an advocacy group that had helped her through her suspension and firing.

After leaving next month, Chambers said, she will relax with her husband in their house in Southern Maryland’s Calvert County, finish half-read books and decorate for Christmas. She said she might even write a book someday.