Freelance mercenaries. These are usually "shirtsleeve" soldiers with requisite military skills, but no equipment or organization other than that provided by their employers. Most of these troops are recruited into national militaries that lack either the manpower, or a loyal enough population to create their own forces from local recruitment. "Foreign Legion" units are generally of this model. The Byzantine Varangian Guard is another example. The term is Gaelic, and refers to the loose groups of Scottish soldiers that travelled to Ireland to fight the Armies of Elizabethan England.