Almost a century ago, James W. Kennedy was among more than 1,100 Boston police officers who walked off the job to protest their working conditions, one of the largest police strikes in US history. On Wednesday, Kennedy’s helmet and baton were returned to Boston Police Department headquarters, unexpected relics from a tumultuous time.

The Rev. Robert Kennedy donated the equipment, which belonged to his grandfather, a patrolman who joined the Boston police force in 1907. Margaret Sullivan, records manager and archivist for the Police Department, said it hopes to display the items in recognition of the 1919 strike.

“We’re coming up on the centennial of the strike, and I expect there will be plenty of opportunities to show this,’’ she said. “It’s wonderful to have equipment that can be connected to a particular officer.’’

Police went on strike in 1919 for higher wages and better working conditions, Sullivan said. Officers were required to work overtime without pay and slept in stations that were often unclean. Their wages hadn’t budged for years.

“There was hyperinflation during World War I, so money didn’t go very far and people couldn’t pay rent,’’ Sullivan said. “They were losing money.’’

Many police officers returned from the war expecting better treatment, Sullivan said. “Each one of the officers who left for the war and came back participated in the strike,’’ she said.

After lengthy negotiations, the officers declared a strike, and chaos quickly broke out.

“Other towns had called strikes and it wasn’t violent, but Boston was different,’’ Sullivan said. “There was gambling on the Common and some violence. The state ended up calling out the state guard.’’

Some officers tried to return to work when violence erupted, but were denied.

“They never came back,’’ Sullivan said. “Everybody lost their jobs, but the people who replaced them got the benefit of higher wages. It called them out as false when they said they couldn’t pay for higher wages.’’

Most officers turned in their equipment when they went on strike, Sullivan­ said. But Kennedy, who lived in West Roxbury, was on vacation at the time and never returned to the department.

“Life was hard for him after the strike,’’ Sullivan said. “He worked at a railroad yard doing the switches on the tracks.’’

Kennedy’s family was dedicated to the police force. His brother, John, also went on strike in 1919 and later joined the Sharon police and eventually became chief, Sullivan said. James Kennedy’s son and grandson also became Boston officers.

Olivia Quintana can be reached at olivia.quintana@globe.com. Follow her on Twitter @oliviasquintana.