Siege Warfare

The pictures below were taken at an exhibition showing the elements of 17th century siege warfare according to Vauban's system of parallels, in the Musée des Plans-Reliefs in Paris.

In the 17th century, sieges followed a prescribed pattern of events, and were often undertaken in a very scientific manner. Vauban formalised many of the 'rules' of siege warfare, drawing up a time-frame for besieging forces to aim for. He also suggested that a garrison should be allowed to surrender with honour if a breach had been made in the walls, to save the needless bloodshed that would ensue if an assault was ordered.

Arrival of the besieging army and construction of the lines of circumvallation and contravallation

When a besieging army arrived at its target, cavalry would be sent to surround the town and cut all the roads leading into the place. Standard protocal dictated that the attackers demand the surrender of the place, but it was expected that the defenders would reject this demand.

The attacking army would then construct earthwork lines surrounding the place at 2400 metres from the defences; one line facing inwards to guard against sorties from the garrison (lines of circumvallation) and one line facing outward to protect the besiegers from enemy forces that might be attempting to break the siege (lines of contravallation).

Besieging troops behind the lines of circumvallation. The besieged town can be seen in the distance.

Between the lines of circumvallation and contravallation, the supplies for the siege would be stored and the troops would camp. Fortified camps often formed strong points in the lines and acted like small forts. The lines were not usually strongly fortified as they were only intended to be temporary works. They were often a simle bank of earth fronted by a ditch and flanked by redans (see picture above).

Digging of the first and second parallels

Digging in batteries adjacent to the zig-zag trenches.

After a careful survery of the defences had been made, the commander of the besieging troops would choose a weak point as the target of the attack. The target was to consist of two bastions and the demi-lune between them. Two zig-zag trenches would be dug forward from the lines towards the targeted section of defences. At 600 metres from the covered way, the first parallel was dug. This was a trench the ran parallel to the defences, linking the two trenches and providing a base for the digging of the first batteries.

These first batteries were sited so as to use ricochet fire along the faces of the target bastions and demi-lune to clear them of guns, limiting the defenders' ability to fire on the trenches. From the first parallel, the two zig-zag trenches were dug farther forward, and the second parallel was created at 320 metres from the covered way. Batteries dug here complimented the work of the batteries on the first parallel, but at closer range they were more effective.

The third parallel and the crowning of the covered way

From the second parallel, three trenches were dug forward, two aiming at the capitals (points) of the bastions, and the middle one aiming for the capital of the demi-lune. At 30 metres from the covered way, the third parallel was dug.

Sappers digging the zig-zag trench towards the fortress. Excess earth is being removed to the rear in wheelbarrows.

The third parallel formed the base from which the assault on the covered way was launched. Its trenches provided shelter for the troops as they prepared to 'go over the top' - in a way similar to fighting techniques in the First World War.

The third parallel has been completed and the attackers prepare to assault the covered way.

The attackers would try to clear the covered way with grenades before the assault and would dig in as soon as they held it. This assault was often the bloodiest part of the siege, as the defenders usually surrendered before an assault was ordered against the main walls.

The Siege of Lille (1708) and the Siege of Maastricht (1673) both witnessed costly battles for control of parts of the covered way. Once the covered way was in possession of the attackers, batteries were dug in there. This was known as the 'crowning of the covered way'. These batteries would start to batter the capitals of the bastions and demi-lune, as well as neutralising the flanks of the adjacent bastions.

Unto the breach...

When a practicable breach (a breach that was ready to assault) has been made in the demi-lune, the attackers tunneled under the covered way and sapped across the ditch towards the breach. The demi-lune was then carried by assault.

Batteries on the covered way are starting to breach the capital of the bastion. The demi-lune (in the background) has been captured.

The attackers could then entrench themselves on the captured demi-lune, and dig batteries there if necessary.

The breach is assaulted and the town falls...

Once a practicable breach had been made in the capital of a bastion, the defenders usually surrendered to avoid more bloodshed. On the occasions that towns were assaulted, atrocities of rape and pillaging often ensued. Vauban always avoided an assault to prevent this from happening.

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