 On 23 September William the Silent followed up on a request by Cabeliau dating from the beginning of the siege and ordered the dikes surrounding Alkmaar to be breached, thereby flooding the polders in which the Spanish troops were camped, like the Achtermeer polder.This forced the Spanish commander, Don Fadrique, the son of the hated Alva himself, to retreat and the last Spanish soldiers left on 8 October 1573.The end of the siege is considered a turning point in the Eighty Years' War as Alkmaar was the first city to overcome a siege by the Spanish army.