The war, known as the Second Northern War, initially took place in Poland-Lithuania. Ascheberg proved to be successful during the campaign. In March 1656. after capturing the city of Jarosław, Ascheberg was promoted Colonel. In July of the same year, he attended the Battle of Warsaw. He commanded the Swedish forces in the Battle of Chojnice (Konitz), in which he was highly successful according to some sources. As a token of his appreciation, Swedish king Charles X Gustav gave von Ascheberg a rapier he had used in battle. von Ascheberg also received valuable jewellery and an estate in Prussia.