Cartel ships depended on agreements the belligerents never made

A cartel ship could carry prisoners, messages, or humanitarian supplies under a mutually recognized agreement and distinctive flags. Britain and the United States had not established that shared procedure when the war began. The separate impressment dispute involved both nationality and proof of citizenship: British officials did not accept that acquiring American citizenship ended a British-born sailor's liability for naval recruitment. Inconsistent or absent papers also made individual claims difficult to establish. Without agreed procedures, officers could not assume that the other belligerent would recognize a cartel ship's protected role.