15. Siege of Ostend, 1601-1604
The ability of sea power to affect military affairs on land was demonstrated dramatically by the over-three-year siege of Ostend, during a series of conflicts known collectively as the 80 Years’ War. The prolonged siege claimed the lives of over 100,000 soldiers, sailors, and civilians, and otherwise accomplished very little. The Dutch defending Ostend were resupplied, and reinforced, by sea, by their own ships and ships and troops from England. The Spanish attackers opened the siege in the summer of 1601 with a series of massive assaults, which were bloodily repulsed, after which the battle turned into one of attrition.
The British adopted the practice of assigning garrisons to the fortifications around Ostend for limited tours of duty before revolving them out. The practice helped minimize disease, often a weakening factor in besieged forces. By the time the Spanish finally took the city in September, 1604, there was a very little city left, it having been leveled by more than three years of continuous fighting. Technically the siege was a victory for the Spanish and a disheartening defeat for the Dutch, but its cost led to the Spanish court collapsing in bankruptcy three years later.