The French military engineer Sébastien Le Prestre de Vauban shaped 17th-century siege warfare. First demonstrated at the Siege of Maastrict (1673), he introduced a scientific approach of attack whereby besiegers would excavate a series of trenches or ‘parallels’, linked by zig-zags called ‘saps’. This network enabled besiegers a safe passage to get closer to the target and in position for a full-scale assault. Lines of circumvallation guarded against escapees and acted as the outer perimeter. The first parallel was positioned approximately 1,970ft (600 m) from the target, at the limit of the defenders’ gun and cannon range. The second parallel, approximately 1,150ft (350 m) from the target, housed sheltered batteries and was positioned to utilize ricochet fire. The third parallel was a base for the assault, and grenades were thrown from here to clear the covered way (the outer edge of the ditch surrounding the fort). Once the attackers had control of the covered way and batteries were put in place, a full-scale fortress assault could begin.
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