So I just finished watching (yeah, yeah) a show about the War of Roses. In several scenes, people shout, "I am ___!" ("I am Henry Tudor!" "I am Anne Neville!") How were their captors 100% sure that they were who they claim to be? Couldn't a commoner just pretend to be someone they're not?
Even if the show was not historically accurate about these bits, how did people identify other people? How often did people lie about who they are? If they mostly told the truth about their identity, why?
There's a brilliant microhistory about this, Davis' the return of Martin Guerre. In it, an early modern French peasant returns to his village after several years of travel, moves back in with his wife, everything seems good. Except a lot of people are convinced he's an imposter. The courts couldn't prove it one way or the other.
Of course, this is a peasant whose identity was only known to his local community. Elites in the War of the Roses often knew one another, and there are clues to suggest whether someone is a king or a peasant in nice clothes (language, knowledge, manners), so the potential for a Prince and the Pauper scenario is limited.
hi! you'll find several examples in this section of the FAQ
If you were conducting business between two peopke, you would have a letter of introduction with the signature/stamp (from a signet ring for example) of someone known to whoever you were talking to. For example there were "canonical letters" in the early medieval period which clerics would carry around with them. They were written by a bishop to signify that the bearer was, indeed, a cleric and entitle to whatever rights a cleric would have.
We have examples of contracts in Egypt preserved in the desert where the signers are physically described with special focus on scars. Check out these descriptions from a land agreement:
Taous daughter of Harpos, about 48 years old, of medium height, fair-skinned, round-faced, straight-nosed, with a scar on her forehead, and her sisters Sennesis alias Tatous daughter of Harpos about 42 years old, of medium height, fair-skinned, round-faced, straight-nosed, with a scar on her forehead, and Siephmous daughter of Pachnournis, about 20 years old, fair-skinned, round-faced, straight-nosed, without mark, all three being Persian women, with their guardian the husband of the said Taous, Psennesis alias Krouris son of Horos, Persian of the epigone, from the village of Gotnit of the lower toparchy of the Latopolite (nome), about 45 years old, of medium height or less, darkskinned, somewhat curly-haired, long-faced, straight-nosed, with a scar on the lower hip.