Concurrently, rebel armies captured cities throughout the entire country, from Deventer to Mons. William himself then advanced with his own army and marched into several cities in the south, including Roermond and Leuven. William had counted on intervention from the Huguenots as well, but this plan was thwarted after the St. Bartholomew's Day Massacre on 24 August, which signalled the start of a wave of violence against the Huguenots. After a successful Spanish attack on his army, William had to flee and he retreated to Enkhuizen, in Holland. The Spanish then organised countermeasures, and sacked several rebel cities, sometimes massacring their inhabitants, such as in Mechelen or Zutphen. They had more trouble with the cities in Holland, where they took Haarlem after seven months and a loss of 8,000 soldiers, and they had to break off their siege of Alkmaar.