Aleid of Poelgeest was the mistress

Mistress

Mistress may refer to:* Mistress , a woman, other than the spouse, with whom a married individual has a continuing sexual relationship* Schoolmistress, or female school teacher...

 of Count of Holland

Count of Holland

The Counts of Holland ruled over the County of Holland in the Low Countries between the 10th and the 16th century.-House of Holland:The first count of Holland, Dirk I, was the son or foster-son of Gerolf, Count in Frisia...

, Albert I of Bavaria

Albert I, Duke of Bavaria

Duke Albert I or Albrecht KG was a feudal ruler of the counties of Holland, Hainaut, and Zeeland in the Low Countries...

.

She was murdered at an early age along with the "Meesterknaap" (a high courtdignitary), William Cuser in The Hague by Hook

Hook and Cod wars

The Hook and Cod wars comprise a series of wars and battles in the County of Holland between 1350 and 1490. Most of these wars were fought over the title of count of Holland, but some have argued that the underlying reason was because of the power struggle of the bourgeois in the cities against...

nobles. Why exactly Aleid was killed, is not certain.

Albrecht saw the murder as a personal attack on his authority and used this event to settle some scores with a number of political opponents.