Born 1606 at Neuhofen an der Krems in Austria, into a family of poor Protestant peasants,[2] Derfflinger had to leave his home due to religious persecution under the Catholic Habsburg dynasty in the course of the Counter-Reformation.

He probably fought side-by-side with insurgent Bohemian nobles led by Jindřich Matyáš Thurn and served in the armed forces of various Protestant combatant powers, at first in the Saxon army, but most of the time in that of Sweden.

Until the 1648 Peace of Westphalia he distinguished himself as an able and daring cavalry leader and gained a reputation for brilliance and bravery, which in 1654 persuaded Elector Frederick William of Brandenburg to offer Derfflinger a senior position in his army.

[4] A lifelong soldier, Derfflinger had no formal education, but was entrusted by the Elector with numerous important military tasks and played a central role in the reform of the Brandenburgian cavalry and artillery.

In order to gain back the Elector's employ, he wrote down a list of incredible demands, which included a clause stipulating that no man charge into battle ahead of him and that he take a certain percentage of plunder and captured officers from every engagement.