The Siege of Wolmar occurred during the Polish–Swedish War (1600–1611), between October 18 and December 18, 1601. Polish forces, numbering around 15,000, with 50 pieces of artillery, led by the Grand Crown Hetman Jan Zamoyski besieged the city (present day Valmiera) defended by about 1,000 infantry under Jacob De la Gardie and Carl Carlsson Gyllenhielm.