Part I

The Romans employed three methods for capturing fortified towns and camps, an art at which they were adept. If the defenses were relatively weak, they might storm them quickly (oppugnatio repentina) without extensive preparations. if, on the other hand, the fortifications were so formidable as to make this impossible or undesirable, I they would resort to a continuous harassment followed by a final assault (expugnatio or oppugnatio). The third method, a. blockade (obsidio), was used when the defenses were too strong to use the first two methods.

Whenever it seemed possible, the Romans stormed a city, town or camp with but slight preparation. Auxiliary troops would drive the defenders from the walls with their missles. Then the ditch or moat around the walls would be filled with brush and earth, and the attackers would move forward with their shields locked in the testudo, trying to break down the gates or wall. Others would attempt to go over on ladders (scalae). For example, Carbulo used this method against the Armenian towns in A.D. 59:

Then forming his army in four divisions, he led one in the dense array of the military "testudo" close up to the rampart to undermine it, while others were to apply scaling ladders to the walls, and many more were to discharge brands and javelins from the engines.

(Tacitus, Church & Brodribb, The Complete Works of Tacitus,p. 307, Tacitus, Annalium, Lib.XIII.39.4: "Turn quadripartito exercitu, hos in testudinem conglobatos subruendo vallo inducit, alio scalas moenibus admoveree . . . ")

If this method failed or appeared impossible, the Romans placed a stronghold under siege. An earthen ramp (agger) would be begun some distance from the walls - beyond easy range of the enemy's missiles and slowly extended toward the enemy fortress. The Romans progressively increased the height of this mound as they moved in toward the enemy fortress, until it was finally level with or even high than the walls themselves. Such a mound might be as much as eighty feet high, and from forty to fifty feet wide. Sometimes wooden galleries were constructed through the length of the earthen mound, so that soldiers could be moved forward under cover.

The workers erecting the agger were protected by lines of mantlets (plutei) - large, movable, upright wooden shields. In order to protect those moving, up earth and supplies, the Romans constructed lines of sheds (vineae) that led back beyond the enemy's effective range. When the workers came so close to the enemy walls that the mantlets could no longer offer effective protection, then strong wooden sheds (testudines) were placed at the end of the mound.

Meanwhile, auxiliaries behind lines of mantlets or posted on movable towers (turres ambulatoriae) rained countless vallies of missiles upon the defenders. Several types of tormenta or missile throwing engines added to the fire by hurling huge javelines or stones against the defenders.

When the Roman siege ramp reached the enemy wall, soldiers moved forward through the interior galleries, and the movable towers - stout timber structures, often several stories high - were rolled forward. The towers were usually made as high or higher than the enemy walls and were furnished with several platforms one above the other, on which attacking soldiers waited.

(Caesar, De Bello Gallico Lib.11.29-31. The sight of Caesar's siege tower and works was enough to induce the Aduatici to surrender.)

When the towers had moved close to the wall on their rollers, the attackers dropped bridges onto the walls, and dashed against the defenders. Others charged up the siege ramp.

Meanwhile, within the mound, the Romans attempted to breech the wall. A huge beam, 60 to 100 feet long and capped with a bronze head, often shaped like that of a ram, would be suspended beneath the wooden shed. A similar battering ram (aries) might hang under a siege tower. With each jaring blow the wall would be weakened until finally the stones would give way.

The Romans might also attempt to dig mines or underground passageways under the enemy walls and enter the city that way. Or else they could set fire to the supporting timbers so that the tunnel would collapse and with it a part of the enemy wall. A third method of breaching was to pull down a high thin wall with huge iron hooks (falces murales) and cables.

As the attackers closed in, the defenders would sometimes pour boiling water, olive oil, molten lead or bronze upon their assailants, or else cast down huge stones and fire brands. Thus the besiegers had to be sure that their works were sturdy and that all the wooden parts were covered with water-soaked green hides.

The defenders would also try to catch up the attackers battering rams and mural hooks with slings, so that they might immobilize them or even draw them up into the city. They tried to meet mines with countermines.

If the Romans could not take a fortress by more active means, they would set up a blockade for starving out the defenders. Old people and children would be driven within the walls to use up the provisions of the besieged. Then strong lines of entrenchment (circumvallationes) would cut off supplies or help for the stronghold.

(3. Onasander, Illinois Greek Club tr., "The General," Aneas Tacticus, Asclepiodotus, Onasander, p. 525; and Caesar, De Bello Gallico, Lib.VII.68-89.)

Part I