Arte et Marte
or from fortress archives

Techniques needed to capture bastioned fortifications were different from those used in the case of medieval fortifications. Obviously, some techniques, such as an unexpected attack or a blockade, separating the fortress from supplies were the same. The so-called “bombardment”, i.e. massive artillery fire was aimed at causing substantial damage, lower defenders’ morale and finally their surrender. However, the most effective technique was always a “regular attack” based on well-defined principles described in many treatises devoted to defensive art. A “regular attack” always consisted of four stages:

• Preparation, which included making a reconnaissance of fortifications of a fortress and building two lines of field earthworks around it (or only on one side of it); the first line, built about 750-1200 m from the attacked fortifications, was to protect the attackers from defenders’ forays and the second line, built about 1350-1800 m, protected attackers from enemy’s relief force. On both lines earthen sconces were made, sometimes joined with embankments. If the lie of the land and military situation permitted it, no lines were built but the existing structures were reinforced, a large number of posts were set up or protecting units were stationed in the area.
• Approaching attack, which consisted in building zigzag ditches towards the attacked fortress to facilitate secret transfer of storming units and artillery. The ditches were directed towards the places of intended attack, usually a bastion or a ravelin, rarely towards the curtain wall. At the bends of the ditches, redoubts were built for artillery batteries. Immediately after a redoubt was completed, guns were brought to the site and firing aimed at the selected place of the fortress commenced.
• Making a breach in fortifications provided a possibility for storming the fortress and capturing it. A breach was most often made by siege artillery. To increase the efficiency of fire, siege artillery battery had to be brought as close to the selected section of fortifications as possible. In order to make 1 sq. m breach, it was necessary to hit the same place with several dozen projectiles. A breach was sometimes be made by means of underground mines. To place a mine under the selected fragment of fortifications, special mining tunnels were made. The entrance to the tunnels was located by the ditch, about 45-90 m from the target. The tunnels were reinforced with wooden fittings and the speed with which they were made was usually about 4 m/day. When the tunnel reached the target, a chamber for cord-detonating explosives was made underneath. Sometimes defenders would build their own counter-tunnels to detonate the counter-mines placed in them and destroy the tunnels built by the enemy. At times counter-tunnels were built together with the fortress, which provided a possibility for quick detonation of mines at the most appropriate places for the defenders. Fortress’s crew would destroy enemy guns and earthworks with their own fire; they would also harass the enemy with forays, killing enemy troops and tunnel-digging miners and destroying canons.
• Storming of a fortress would start once a breach (or several breaches) was made. Attackers had to first force their way through the moat whose banks had had to be destroyed (sometimes the moat had to be filled in) to provide them with a comfortable descend. They also had to endure the fire of guns located on bastion flanks and the fire of cannons located in caponiers* and finally get through the breach in the fortifications and defeat defenders in hand-to-hand combat. The task was not an easy one; it was very hard to capture a properly-built and well-provisioned fortress. Sieges often lasted many months, involving many troops of the attackers. Sometimes, however, powerful fortresses under poor command surrendered very quickly, notwithstanding mighty fortifications.