Dozens of New Orleans firefighters erected cardboard gravestones as a trumpeter played taps at Duncan Plaza on Tuesday, a display meant to represent more than 100 of their colleagues who died while they were still owed money in a decades-long dispute with the city over back pay.

The macabre protest came as firefighters prepare to move into the next phase of a legal battle with the city over that money. It was part of a broader public relations blitz by the firefighters — dubbed the Fairness for Firefighters campaign — calling attention to a wide range of grievances through ads on WWL-TV and Fox 8, as well as billboards.

“We want to fight fires. We don’t want to fight City Hall,” said Nick Felton, president of the firefighters union.

The back-pay issue, known as the “longevity suit,” has been bouncing through the court system for decades. The firefighters want money for raises they say were legally mandated by the state but never provided by the city. They have won every round in the courts but have been unable to collect the $75 million the city owes them.

The next step in the process is expected to come Thursday, when Civil District Court Judge Kern Reese hears arguments from the firefighters for holding city officials, including Mayor Mitch Landrieu and the City Council, in contempt because they haven’t paid up.

Tuesday’s rally focused largely on that case and the 111 firefighters who were owed money but died while the lawsuit has made its way through the courts. The most recent addition to that list was Emile Lotz, a retired firefighter who died on May 30 at the age of 71.

“They don’t want anything extra; they don’t want a reward,” former Fire Superintendent Charles Parent, whose brother is one of the firefighters who died during the court battle, said at the rally. “They just want what’s due to them.”

Firefighters have also taken the Landrieu administration to court over its failure to pay into their pension system in recent years as city officials accused the fund’s board of mismanagement that contributed to a sharp decline in its assets. The courts also have ordered the city to pay up in that case.

Felton also called Tuesday for increased funding for fire protection, arguing that the department’s staffing is 33 percent below what it should be and that many of its trucks are aging and need replacement.

Landrieu spokesman Brad Howard focused on the pension dispute in an emailed statement responding to the rally, saying the union’s leadership has failed to take responsibility for fixing the key issues facing firefighters.

Rolling the issues of back pay and the pension fund together was a key element in three of the four plans presented earlier this year to a task force charged with resolving the disputes and finding a way to put the essentially insolvent pension plan, which has seen its account balances plummet due to failed investments, back on a sustainable path.

But firefighters rejected those proposals, which would have required that they give up some or all of the money they won in the longevity judgment.

Administration officials have said the city does not have the money to pay out the court judgments and that doing so would cause steep cuts in other city services.

“Rather than working with all parties, their ‘my way or the highway’ approach threatens the city’s ability to deliver essential services residents depend on, such as public safety, street repairs and parks and recreation,” Howard said. “The city remains deeply interested in having good-faith, productive discussions as we work together to fully resolve these challenges.”

Firefighters at the rally, however, called for action by the city.

“I hope I get my money before I’m the next tombstone,” Robert Ruther said.

Follow Jeff Adelson on Twitter, @jadelson.