While he travelled to England in 1382, 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 Dunkirk in May 1383. When the count died in 1384, he was succeeded by Philip the Bold, Duke of Burgundy who had married Margaret III, Countess of Flanders, the daughter of Count Louis. Duke Philip continued the war. 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.
On 18 December 1385, the war ended with the Peace of Tournai between Ghent and Philip the Bold.
Ackerman was murdered two years later by a son of the Lord of Herzele who deemed him responsible for the death of his father.