His duties are described in detail by the king's regulations, but may be summed up as consisting of seeing that the charges are in order, pointing out any informalities or defects in the charges or in the constitution of the court, seeing that any witness required by prosecutor or prisoner is summoned, keeping the minutes of the proceedings, advising on matters of law which arise at any time after the warrant for the courtmartial is issued, drawing up the findings and sentence, and forwarding the minutes when completed to the admiralty.
Yet on the 3rd of October 1865, Maximilian, misled by a false report that Juarez had left the country, issued a decree declaring the Juarists guerillas, who, whenever captured, were to be tried by courtmartial and shot.
But Kearny's authority being confirmed about the 1st of April, Fremont, for repeated acts of disobedience, was sent under arrest to Washington, where he was tried by courtmartial, found guilty (January 1847) of mutiny, disobedience and conduct prejudicial to military discipline, and sentenced to dismissal from the service.
A courtmartial condemned him in contumaciam to death by "garote vil," and he had to hide in the house of a friend until he escaped to France.
There he was tried by courtmartial, and on the 10th of February was shot, twenty-four hours after his condemnation.