It's no exaggeration to say mercenaries were the unsung heroes of the Hundred Years' War.
With its entire territory ravaged by the Hundred Years' War, France couldn't rely on militias and instead hired foreign mercenaries in droves to fight England. Sure, there were still bandit-like mercenary bands here and there, but the war completely changed how people viewed mercenaries.
European history is basically a history of war. On a small scale, neighboring territories fought each other, and on a large scale, there were massive wars between nations like the Hundred Years' War. Victory or defeat often came down to who hired better mercenaries in greater numbers.
That's why the mercenary business became a new frontier where medieval people could strike it rich.
