Why was Frederick William called the Great Elector after the 1675 campaign against Sweden?

Frederick William, the elector of Brandenburg, earned the title "the Great Elector" following his military success against Sweden during the Scanian War.

In June 1675, Frederick William led his army to a decisive victory over Swedish forces at the Battle of Fehrbellin. This engagement was significant because it marked the first time his military force—which he had painstakingly built to establish independence and combat the privileges of local estates—achieved an independent victory under his direct command. Following this triumph, he was referred to as the "Great Elector" for the first time in a contemporary folk song.1

This victory served as a turning point in his efforts to reclaim territories lost during the Thirty Years’ War and demonstrated the growing prowess of the standing army he had developed, which would eventually become the core of the 18th-century Prussian military.21