When settlers first started coming from Europe in large numbers to live on the North American continent, there were no official police forces and no way to protect one's self unless there was enough money to hire a private security guard. Now these guards weren't the same as you'd see today where a Natomas private security company might be hired to guard a specific business or residence for an amount of time. Early private security guards were more often the type of person to be hired almost as a mercenary and without legal training to keep the streets of a particular town safe.