What is an unsigned passport?

[susan]

The Passport: The History of Man’s Most Travelled Document

The Ancient Egyptians were known to have a passport system while, in Roman times, persons travelling on official business were issued with a Tractorium (a letter) in the name of the emperor. Yet contrary to the popular idea, passports were often used to prevent not facilitate travel. William the Conqueror allowed no one to enter or leave England without his permission while Henry I and Elizabeth I refused to grant passports to, respectively, the legate from the Pope and Mary, Queen of Scots.

It’s not a bad book for a couple of bucks.