OTTAWA -- The head of the military support unit for injured soldiers is stepping down after only three months on the job, leaving the much-maligned organization facing its third leadership change in less than a year.

Military officials are playing down the impact that Brig-Gen. Shane Brennan's surprise resignation will have on the Joint Personnel Support Unit, which he was brought in to overhaul.

But Brennan's departure nonetheless raises questions about the unit and its future, particularly since his immediate predecessor also left suddenly after only six months in the position.

The JPSU was established in 2008, at the height of the war in Afghanistan, and comprises 24 support centres and eight satellite offices on military bases and in communities across the country.

The aim is to help physically and mentally wounded personnel heal and return to their units, or prepare for medical release and transition into the civilian world.

But the unit has been plagued with problems and complaints related to chronic understaffing, poor training for those who do work in the unit, and inadequate access to treatment and support.

Some military personnel assigned to the unit have since taken their own lives.

Brennan took over the JPSU to much fanfare in April, and was touted as the right person to make good on defence chief Gen. Jonathan Vance's promise to overhaul the entire organization.

Before that, Brennan had been working in Kuwait, where he was responsible for overseeing much of Canada's war against the Islamic State of Iraq and the Levant.

But the job of fixing the JPSU will now fall to another officer, as military officials announced Friday that Brennan and his wife, Maj.-Gen. Tammy Harris, are both retiring from the military.

Harris's departure is also noteworthy: she only recently become deputy commander of the Royal Canadian Air Force, the first woman to hold such a position within one of the military's three services.

But Brennan's decision continues to turn what has become a virtual revolving door at the top of the JPSU since the sudden resignation of its longest-serving commander, Col. Gerry Blais, in February 2016.

Blais was replaced on an interim basis by navy Capt. Marie-France Langlois until Brig.-Gen. Dave Corbould took over last August with promises that he would be the one to turn the page on the JPSU's problems.

Corbould lasted only six months in the job, however, before hanging up his uniform in February.

Lt.-Gen. Charles Lamarre, head of Military Personnel Command, would not get into details, but said Brennan and Harris had decided to leave for personal reasons after a combined 65 years in uniform.

"They looked at where they had been, how much time they'd spent away from each other, and the challenges ahead of them," Lamarre said in an interview.

"And they made a call. They said they're actually at a point now where they're going to move on and retire from the Canadian Armed Forces."

Lamarre acknowledged the sudden change isn't ideal, but he insisted that efforts to fix the JPSU and eventually expand it to ease the transition to civilian life for all retiring personnel will move as planned.

That starts with Brig.-Gen. Mark Misener, who is currently in charge of the 4th Canadian Division Support Group at CFB Petawawa, but will take command of the JPSU on July 20.

Misener brings not only essential leadership and planning skills to the position, Lamarre said, but also a commitment to sticking with the job for the long term.

"We're asking for this individual to be fully committed for a good, solid three years," Lamarre said. "And Mark Misener is fully aware of that responsibility, and he's ready for it."

The fact Brennan was only in the position a short time also means that efforts to overhaul and expand the JPSU are still in their infancy, Lamarre added, which should ease Misener's move into the position.

"I believe this will be no interruption in the work that's being planned," Lamarre said.