Ostend was resupplied via the sea and as a result held out for three years. A garrison did a tour of duty before being replaced by fresh troops, normally 3,000 at a time keeping casualties and disease to a minimum. The siege consisted of a number of assaults by the Spanish, including a massive unsuccessful assault by 10,000 Spanish infantry in January 1602 when governed by Vere. After suffering heavy losses the Spanish had replaced the Archduke with Ambrosio Spinola and the siege settled down to one of attrition with the strong points gradually being taken one at a time.