From Robert Randall and the Le Breton flats...:
In 1811 [Captain John LeBreton] was stationed as a Lieutenant in the QuarterMaster Generals Department at Quebec. In this office he seems to have been active and zealous in the performance of his duties. On the outbreak of the war in 1812, between Great Britain and the United States, he was attached to the Royal Newfoundland Regiment of Fencible Infantry, a regiment which earned an enviable record during the war. He accompanied the regiment on General Brock's expedition to Detroit in 1812 and was present at the capture of the city.
See John LeBreton's biography here.