The Siege.
The Romans excelled in the art of taking walled cities, and this skill gave them an immense advantage in their warfare with semi-barbarous and ignorant peoples. There were three methods of doing this: first, by an
immediate attack (
oppugnatio repentina); second, by an active siege,
brought to a close by an assault (
expugnatio); third, by investment and blockade (
obsidio).
If there seemed to be a chance of success, a city was stormed at once with no formal preparation (
ex itinere). Its defenders were driven from the walls by a shower of missiles (
Bk. iii. 25); the moat was filled with brush and earth; the assaulters with shields locked in a
testudoattempted to break open the gates or scale the walls with ladders.
If this method proved unsuccessful or impossible, a regular siege was begun. The work of a regular siege centred about the mound or
agger, and to its construction everything else was subordinated. It was begun at a distance from the wall, very nearly out of reach of the missiles of the enemy. It was then gradually extended in the direction of the point to be attacked, and was at the same time gradually increased in height until on a level with the top of the wall, or even higher. At Avaricum the mound was 80 feet high (
Bk. vii. 23-28.) Its width was possibly 40 or 50 feet. It was made of earth and timber, and hadconnected galleries running through its various stories, through which the
soldiers could move under cover (see Fig.
120). The men engaged in constructing the
agger had to be protected from the enemy. Those who were building worked behind lines of
plutei (see Figs.
130,
131), large standing shields which were moved forward from time to time as the
agger progressed. Those bringing material for the builders walked under rows of sheds called
vineae (see Figs.
33,
120), extending the length of the
agger. The workmen were protected also by archers and slingers and by
engines of war (
tormenta) standing behind lines of
plutei or upon movable towers (
turres). The latter stood on the
agger or on either side of it, and advanced with it, and as they advanced increased in height story by story. As the workmen get nearer the wall the
plutei will no longer protect them. Then they find refuge under strong sheds of wood called
testudines or
musculi, placed at the ends of lines of
vineae.
When the mound has reached the wall, a breach is made through it for the final assault (
expugnatio). Sometimes this was accomplished by undermining the wall, or it was pulled down from the top with huge iron hooks (
falces murales). But the most common and most effective means was the battering ram (
aries), a huge swinging beam from 60 to loo feet long with a heavy mass of metal at one end, often shaped like a ram's head. This under a
testudo, or in the lowest story of a tower, was brought with tremendous force against the opposing masonry. When the final assault was made, soldiers rushed in from every quarter, over the mound, through the breach, and from the movable towers, from whose highest stories drawbridges stretched to the walls.
Against these forms of assault the inhabitants used such means of resistance as they could. The most effective were masses of stone, thrown from the wall upon the works, and fire. To guard against the latter, the besiegers had to cover all exposed woodwork with green hides. Battering rams and mural hooks were caught in slings and held fast, or drawn into the city, and mines were met by countermines. See Figs.
92,
93,
127.
When the location of the place was such that it could not be taken by such a siege as that described above, it was invested on every side (
obsidio) and the inhabitants starved into submission. Among sieges of this kind were those of Gergovia (
Bk. vii. 44-53) and Alesia (
Bk. vii. 72-80), of which the last was one of the most remarkable of ancient times see Figs.
97,
102.
