In 1631 Poyntz fought for John George of Saxony at the Battle of Breitenfeld. He changed sides and fought as a captain in Wallenstein's army in the service of Emperor Ferdinand II at the Battle of Lützen in 1632. He remained in the Imperial army and the following year he campaigned in Silesia and was present at the Battle of Nordlingen in 1634. He left the army and Germany after the Peace of Prague in 1636. His time in Germany was lucrative and he bought an estate probably in the vicinity of Schorndorf. He returned to England that year and wrote his "Relation", but when he failed to fined employment as a soldier in England, it is likely that he returned to the continent to find further employment in the Thirty Years' War. He may have risen to the rank of sergeant-major, and may have been knighted on the battle-field.