Not much is known about the Musketeer, except that he was inspired by Batman and the stories of the Justice Society to take a costumed identity as the hero of Paris. He was involved in the Club of Heroes for its brief existence.
Years later, when Doctor Mist set up the Global Guardians, the Musketeer was among the founding members. However, he vanished under mysterious circumstances and was not seen again for years.
Years later, the truth was revealed: the Musketeer was involved in an incident with one of his enemies, when he accidentally stabbed the other man and was convicted of manslaughter. He was sent to prison with his rogues gallery for an extended period, an experience he did not enjoy; however, he has since written a book about the experience and sold the movie rights, making him rich.
He responded willingly to Batman's call for the Club of Heroes to meet once again.