The castle of the middle ages up to the invention of the bombard was practically that of the ancient “castellum,” as far as defence was concerned, with outworks frequently of wood; and the means of attack lay in escalade, sapping and mining, the use of the battering-ram, or by a blockade.

We now touch upon the machines used in attacks on fortified places, most of which have their prototypes during ancient times in the testudo, pluteus, tenebra, etc.

The battering-ram, the tenebra of the Romans, used both on land and sea, was a heavy oak beam tapering towards the head, which was shod with iron with a point at the extremity. It was exactly the same in the middle ages as in Roman times. There is a Roman specimen in the Germanische Museum at Nuremberg, which is about a foot in diameter at the base, and about eleven feet in length. It is still shod with iron.

Sometimes in the middle ages this machine was made available for the united energies of many men, by means of beams joined together and suspended in a sling or massive trestle, whereby its force could be enormously increased. It was sometimes impelled on rollers or wheels and rapidly run forward to batter a wall. An engine similar to this is figured at Nineveh. The besieged did their best to deaden its effect by means of woolsacks or bags of hair let down from the parapet.

The “sow” or “cat,” the vinea of the Romans, is a shed on wheels, covered with raw hides, used as a cover for preparing the way for the use of movable towers and other engines. This machine is the ancient “pluteus.”

The testudo (testa, a shell), the more modern “tortoise,” was also a movable shed like the cat, but it contained a battering-ram for attacking a rampart.

The berefreid, beffroi or belfrey, is a movable tower used for scaling walls. It was constructed in several storeys, with intercommunications by means of ladders or staircases, and high enough to overtop the parapet of the fortress assailed; provided with a drawbridge for an assault in force, and was often rolled on wheels to the point of attack. A machine of this kind, built by order of Simon de Montfort, was used at the siege of Toulouse, and, according to the ballad of the “Albigéois,” was adapted to contain five hundred men. The last of these engines was constructed as late as the reign of Charles I., and it was taken by the parliamentary forces.

Mantlets stuck in the ground provided shelter for the archers, and other combatants, beneath the walls, against “Greek fire,” showers of rocks, and other missiles, hurled from the battlements by the defenders.

“Greek fire” was used both in attack and defence. This was a Greek invention, as its name implies, and the secret of its composition was most jealously guarded. It was known in the east of Europe as early as 673, and was for a long time regarded as supernatural by the northern nations in the “dark ages,” but the secret was discovered by the Crusaders—in fact, Philip of France brought some of it from Acre, and used it for setting fire to the English ships at the siege of Dieppe. Jesuit Petavius states on the authority of Nicetas, Theophanes, and Cedrenus, that it was invented about the year 660.43 Anna Comnena gives the ingredients as bitumen, sulphur, and naphtha; and states that the Emperor Alexius discharged it at the enemy from his galleys. Others add pitch and gum to these ingredients. It was used in many ways, but its most fatal and irresistible form of application was in setting fire to fortified towns, where the wooden houses of mediæval times afforded it free scope, when inadequately guarded against by a sufficient application of raw hides to the roofs, and other means of protection. A mixture of vinegar, sand, and urine was used to put out its flames. Barrels of “Greek fire” were fired into these towns from the ancient “trebuchet,” and also by a kind of mortar; it was also freely used by the besieged for the destruction of movable towers and engines of war. Froissart, in his account of the attack by the Black Prince on the castle of Romorantin on the Sandre, mentions an engine he calls an “aqueraux” to fire “le feu gregois.”