Ackerman was born in
Ghent. Rallying to
Philip van Artevelde in the
Ghent Revolt of 1379 against
Louis II, Count of Flanders, Ackerman was placed in command of the
Reisers, a mobile force of 3,000 men responsible for securing the city's supply-lines with Liège, Brussels and Leuven. He distinguished himself in the
Battle of Beverhoutsveld (3 May 1382), which led to the taking of Bruges and put almost all of Flanders under the control of Ghent. With the king of France lending support to the count of Flanders, Ackerman undertook an embassy to England to seek the intervention of
King Richard II. During his absence, the rebels suffered a serious defeat in the
Battle of Roosebeke (27 November 1382), where Van Artevelde himself was slain. The count regained control of all of Flanders except the city of Ghent, where Ackerman became the rebel leader. The English launched
Despenser's Crusade in 1383, intervening in Flanders under the pretext of enforcing obedience to
Pope Urban VI. Ackerman took
Aardenburg from a French garrison, sacking the town and carrying the plunder to Ghent, and made an unsuccessful attempt on Bruges. Together with his English allies he was victorious at the
Battle of Dunkirk (25 May 1383). He then took
Oudenaarde by stratagem. When the count died in 1384, he was succeeded by
Philip the Bold, Duke of Burgundy, who had married the count's daughter,
Margaret III, Countess of Flanders. Duke Philip continued the war. Ackerman took the town of
Damme in a surprise attack, but was soon besieged within it by the army of
Charles VI of France. The expected help from the English not arriving, his force broke out and returned to Ghent. On 18 December 1385, the war ended with the
Peace of Tournai between Ghent and Philip the Bold. Ackerman was a prominent member of the Ghent delegation who agreed the terms, but afterwards declined to serve the duke either at court or in the field. On 22 July 1387, while on his way to
Saint Peter's Abbey, Ghent, Ackerman was murdered by a son of the Lord of
Herzele who blamed him for his father's death. ==References==