Later Periods

During later periods, particularly in Western Europe, the nature of investment changed considerably. Rather than concentrating entirely on closing the gates, the attacker would often go to great efforts to totally enclose the castle within siegeworks, often elaborate enough to be considered strongholds in their own right. Such an enclosure often comprised two distinct systems of walls and trenches: lines of “circumvallation” (facing the country) and “countervallation” (facing the besieged fortress). These siegeworks first appeared as tentative experiments around Milan in 1522 and grew into the elaborate constructions besieging Grave in 1602.

The principle of complete encirclement had a number of benefits in a gunpowder-free campaign (and many more when siege cannon were available). The first was defense for the attackers. Rather than taking up positions to guard the gates-often nearer to the walls than was comfortable-and having to suffer withering fire from the battlements, the attackers could shelter behind ramparts and breastworks.

The siegeworks also provided defense in depth. To break out of the encirclement, a sortie would have to leave the castle, cross the “no-man’s-land” between it and the siegeworks-a prime killing ground, should the attacking force have any number of archers or musketeers at all-then fight its way over or through the attackers’ own fortifications. This would typically prove much more difficult than bursting through a relatively small force encamped directly outside the gate.

Complete encirclement made it much more difficult for the defenders to send word of their predicament to allies who could come and relieve them. Finally, should relief finally come to the besieged fortification, the attackers would be deeply entrenched, equally ready to repel a sortie from within or an attack from without.