Sir John Colborne, the military commander in British North America, initiated the court martial. In preparation, he declared martial law, suspended habeas corpus, and forbade other courts from trying or bailing anyone charged with treason or suspicion of treason. He appointed Major General John Clitherow as president of the court martial, with 15 other officers acting as judges.
Fortunately, Lower Canada did not have a legal equivalent to the Lawless Aggressions Act used against prisoners in Upper Canada. Patriote prisoners could and did call witnesses in their defense and vigorously cross-examined the prosecution witnesses.
The Lower Canada judge advocates tried the senior officers alone and the rank and file in groups of between three and 19. Unlike the trials of captured Hunters in Kingston, where a group of men were tried and convicted in as little as an hour, the Patriote trials lasted between three and eight days. Much of that time passed as prisoners presented defense witnesses. Whereas the Upper Canada court martial managed to try 140 men in five weeks in Kingston, Clitherow and his officers spent five months to try 108 men.
In Montreal, the court accused 10 men of murder as well as treason. Murder convictions were flawed. The British treated a death of one of their own during a battle as murder. In most cases, no witness could positively identify the accused murderer because he was just one of many shooting at the time. The proximity of the accused to the victim seemed to be all the court needed to convict. Five accused murders hanged, three were transported, one was acquitted, and one was allowed bail.
In Montreal, the officers recommended a reduced punishment for 21 men sentenced to hang. Of those, 12 were released on bail or exiled and the rest transported.
While the legal process in Lower Canada met the British standards of justice for the time, the execution rate paralleled that of Upper Canada. Eleven of 140 men tried in Kingston hanged compared to 12 of 108 men court-martialed in Montreal. In both cases, hangings tended to apply to leaders. All those hanged met their fate in the Pied-du-Courant Prison in Montreal in three groups: December 21, 1838, January 18, 1839, and February 15, 1839.
Besides those hanged, authorities transported 58 to a penal colony in Australia, acquitted eight, exiled three from the colony, and granted bail to 26.
The transportees set sail on the Buffalo September 28, 1839, with 60 Hunter raiders from the Battle of the Windmill, 18 Patriots taken in raids near Detroit, and five common criminals. They landed in Australia near Sydney at a place still called Canada Bay February 26, 1840, after a stop in Tasmania to drop off their American compatriots.
The convicts spent two years in slave conditions building roads. In 1842, they received their tickets to leave, allowing them to work for wages if they cold find jobs. Between 1843 and 1844, Britain pardoned them. Except for two that died and one who stayed, they eventually all returned to Canada.
Further ReadingRead the second installment of this two-part Patriote finale.
You can find details of the trials in two volumes on the Internet through Google Books. Search for "Report of the state trials, before a general court martial held at Montreal in 1838-39."