 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 . 
