On September 17, Brigadier General Richard Montgomery, now commanding the American forces, began to besiege Fort St. Jean. The next day, a detachment of American forces under the command of John Brown arrested Hazen north of the fort. However, a British sortie from the fort forced Brown's men to retreat; Hazen ended up in British hands. Major Charles Preston, the British commander, was mistrustful of Hazen, and sent him to Montreal under the guard of Claude de Lorimier. Brigadier General Richard Prescott, unhappy with Hazen's explanations of his movements, imprisoned him.