Mercenaries are more powerful than experts realize, a grave oversight. Those who assume they are cheap imitations of national armed forces invite disaster because for-profit warriors are a wholly different genus and species of fighter. Private military companies such as the Wagner Group are more like heavily armed multinational corporations than the Marine Corps. Their employees are recruited from different countries, and profitability is everything. Patriotism is unimportant, and sometimes a liability. Unsurprisingly, mercenaries do not fight conventionally, and traditional war strategies used against them may backfire.
Used availability for Sean McFate's Mercenaries and War
December 2019 : USA Paperback
December 2019 : USA, Australia, Canada, UK Kindle edition