"After the disastrous battle at Moraviantown where the British were badly defeated and were obliged to retreat to the Niagara River, giving up the whole western portion of the Province, LeBreton volunteered and was sent with a flag of truce to General Harrison to arrange for an exchange of prisoners." [Source]
More about what happened in the aftermath of LeBreton's encounter with General Harrison (excerpted below*):
*"General Harrison received, by messenger Lieutenant Le Breton, a letter from Major General Proctor dated October 18th (place of writing not given) addressed to him at the Moravian towns by the Thames but delivered at Detroit before his departure from that place."
"Lieutenant Le Breton was given good opportunity to see that the proprieties of civilization had been complied with in regard to the British. He was not permitted to return by land, however, but was taken across Lake Erie in boat with General Harrison."
Note: In other actions, LeBreton was severely wounded at Lundy's Lane.