While he travelled to England, in an attempt to find support for Flanders against the attacking French, Van Artevelde died in the Battle of Roosebeke and all Flanders but Ghent was subdued by Count Louis. Back in Ghent, Ackerman took the place of Artevelde and fought victoriously in the Battle of Dunkerque. Even though the count died in 1384, the war was not over. Ackerman conquered the city of Damme and was soon beleaguered by the army of Charles VI of France. The expected help from the English failed to appear, and he had to break the siege on his own.
Ackerman was murdered two years later by a son of the Lord of Herzele who deemed him responsible for the death of his father.