create_unit usage

What is the proper format for using "create_unit" in MedievalShell?

For the purposes of this question, I am trying to add a unit of Crusader Knights, whose Shell name is Crusader_Knights

I enter: create_unit crusader_knights
and I get back: err: character or settlement not found

How to I execute this command properly?

Nevermind, figured it out. For future search function reference:

create_unit "London" "Crusader Knights"

captialization counts and no underscore in the unit name