Bibracte 58 BC

[aligern]

Bibracte 58 BC

Protagonists

Roman army of the Gallic Province
6 legions, two of new recruits so 28,000 legionaries, 5,000 cavalry,perhaps 3-4,000 light troops.


The Helvetii, Boii and Tigurini

By Caesar's numbers 368,000 persons and around 90,000 combatants.
Of which 500 cavalry.
These are highly speculative figures, perhaps a doubling of the tribes' effective strength.

Source, Caesar's Gallic War Book I, chapter 23 ff.
At the Internet Classics Archive.






Chapter 23

The next day (as there remained in all only two day's space [to the
time] when he must serve out the corn to his army, and as he was not
more than eighteen miles from Bibracte, by far the largest and best-stored
town of the Aedui), he thought that he ought to provide for a supply
of corn; and diverted his march from the Helvetii, and advanced rapidly
to Bibracte. This circumstance is reported to the enemy by some deserters
from Lucius Aemilius, a captain, of the Gallic horse. The Helvetii,
either because they thought that the Romans, struck with terror, were
retreating from them, the more so, as the day before, though they
had seized on the higher grounds, they had not joined battle or because
they flattered themselves that they might be cut of from the provisions,
altering their plan and changing their route, began to pursue, and
to annoy our men in the rear.

Chapter 24

Caesar, when he observes this, draws off his forces to the next hill,
and sent the cavalry to sustain the attack of the enemy. He himself,
meanwhile, drew up on the middle of the hill a triple line of his
four veteran legions in such a manner, that he placed above him on
the very summit the two legions, which he had lately levied in Hither
Gaul, and all the auxiliaries; and he ordered that the whole mountain
should be covered with men, and that meanwhile the baggage should
be brought together into one place, and the position be protected
by those who were posted in the upper line. The Helvetii having followed
with all their wagons, collected their baggage into one place: they
themselves, after having repulsed our cavalry and formed a phalanx,
advanced up to our front line in very close order.

Chapter 25

Caesar, having removed out of sight first his own horse, then those
of all, that he might make the danger of a11 equal, and do away with
the hope of flight, after encouraging his men, joined battle. His
soldiers hurling their javelins from the higher ground, easily broke
the enemy's phalanx. That being dispersed, they made a charge on them
with drawn swords. It was a great hindrance to the Gauls in fighting,
that, when several of their bucklers had been by one stroke of the
(Roman) javelins pierced through and pinned fast together, as the
point of the iron had bent itself, they could neither pluck it out,
nor, with their left hand entangled, fight with sufficient ease; so
that many, after having long tossed their arm about, chose rather
to cast away the buckler from their hand, and to fight with their
person unprotected. At length, worn out with wounds, they began to
give way, and, as there was in the neighborhood a mountain about a
mile off, to betake themselves thither. When the mountain had been
gained, and our men were advancing up, the Boii and Tulingi, who with
about 15,000 men closed the enemy's line of march and served as a
guard to their rear, having assailed our men on the exposed flank
as they advanced [prepared] to surround them; upon seeing which, the
Helvetii who had betaken themselves to the mountain, began to press
on again and renew the battle. The Romans having faced about, advanced
to the attack in two divisions; the first and second line, to withstand
those who had been defeated and driven off the field; the third to
receive those who were just arriving.

Chapter 26

Thus, was the contest long and vigorously carried on with doubtful
success. When they could no longer withstand the attacks of our men,
the one division, as they had begun to do, betook themselves to the
mountain; the other repaired to their baggage and wagons. For during
the whole of this battle, although the fight lasted from the seventh
hour [i.e. 12 (noon) 1 P. M.] to eventide, no one could see an enemy
with his back turned. The fight was carried on also at the baggage
till late in the night, for they had set wagons in the way as a rampart,
and from the higher ground kept throwing weapons upon our men, as
they came on, and some from between the wagons and the wheels kept
darting their lances and javelins from beneath, and wounding our men.
After the fight had lasted some time, our men gained possession of
their baggage and camp. There the daughter and one of the sons of
Orgetorix was taken. After the battle about 130,000 men [of the enemy]
remained alive, who marched incessantly during the whole of that night;
and after a march discontinued for no part of the night, arrived in
the territories of the Lingones on the fourth day, while our men,
having stopped for three days, both on account of the wounds of the
soldiers and the burial of the slain, had not been able to follow
them. Caesar sent letters and messengers to the Lingones [with orders]
that they should not assist them with corn or with any thing else;
for that if they should assist them, he would regard them in the same
light as the Helvetii. After the three days' interval he began to
follow them himself with all his forces.
Commentary:T

he Helvetii, occupiers of modern Switzerland had decided to migrate en masse,under pressure from German tribes. To get into Gaul and establish a new territory they must pass through the Roman Province which Caesar forbids. As the Helvetii try to find a route Caesar dogs their path, cutting off the rearguard. As Caesar makes a diversion to re-supply the Helvetii advance and seek battle. Caesar uses his cavalry to delay the Gauls.
Caesar, puts his four experienced legions to the front in three lines. He protects his auxiliaries and the two recently raised legions. Thus he is probably using only 16-18000 troops. On that basis I find it hard to believe that the Helvetii have huge numbers.

The importance of the battle is that it is where Caesar describes standard Roman and Gallic tactics. The Gauls form a phalanx with overlapping shields and advance up the hill. The Romans throw pila which pin the Gallic shields and disorganize the phalanx and then charge in with the sword to slaughter the now shieldless front ranks. The sequence is quite clear. It is possible that behind Caesar's terse prose lies a period of more prolonged missile throwing, but the sense of his words is better served  by a mass throw with a rapid follow up.
The Gauls are driven down the hill for 1000 yards and then the  Boii and Tulingi arrive and attack the Roman flank. In a display of superior Roman command and control Caesar has his third line deal with the flank attack. The Gauls retreat to their wagons and fighting goes on until nightfall.

To reconstruct this battle it would be necessary to allow the Gauls to be driven back a long way by the Romans and to have the flank attack come in as a surprise.

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