No reason was given for the departure of Driscoll, who is a friend of Vice President JD Vance, but tensions with Defence Secretary Pete Hegseth have been widely reported.
It marks the latest in a series of shake-ups of the military leadership, with the Army especially seeing major upheaval.
A US Army official, who was not authorised to comment publicly and spoke on condition of anonymity, said Driscoll spoke with President Donald Trump on the current state of the Army and submitted his resignation.
His departure comes after Hegseth ousted several other generals and admirals, including the head of the Navy.
The Pentagon abruptly announced in April that Navy Secretary John Phelan was leaving the job, becoming the first head of a military service to depart during Trump’s second term.
Driscoll’s exit also follows the ouster of one of his allies from the Army as well as the rollback of a drone programme he had championed.
Hegseth had suddenly gotten rid of the service’s top uniformed leader, General Randy George, in April, while the Army’s commander in Europe and Africa, General Christopher Donahue, unexpectedly stepped down in June.
General Christopher LaNeve, who has made a meteoric rise under Hegseth, took George’s place as the Army’s acting chief of staff.
Under LaNeve, the service is pulling the plug on a drone modernisation programme.
An Army unit based in Europe was building its own drones before LaNeve directed it to end its efforts and return to being a traditional infantry battalion, officials said in August.
Driscoll was a George ally and lamented his departure, along with both Republican and Democratic lawmakers. He told Congress in April that he and his family drove to George’s house following his resignation “and we all gave him a hug.”
Driscoll is an Iraq war veteran, tech investor and former adviser to Vance, whom Driscoll met at Yale Law School. When nominating Driscoll in 2024, Trump called him “a disruptor and change agent.” (AP)
