Before leaving for Italy, Caesar sends Servius Galba with the Twelfth Legion and some cavalry to the districts of the Nantuates, the Veragri, and the Seduni. Galba is to open a travel route through the Alps for Roman traders, who now have to pay heavy tolls. Caesar also gives him permission to winter in the area if necessary.
After several successful engagements, the Romans open the route, and Galba stations two cohorts among the Nantuates, then moves the rest of his troops to a hamlet of the Veragri; Octodurus is chosen, a location surrounded by high mountains and having only a bit of level ground. Furthermore, the town is divided by a river; Galba is pleased by this arrangement and assigns the Gauls to one side and establishes his camp on the other.
Several days later, Galba's scouts inform him that the Gauls have slipped out of their hamlet during the night and are now on the heights surrounding his camp. Because of the location, the Seduni and the Veragri feel that now they can easily eradicate the Roman units. They fear that the Romans intend to take over all the Alpine territory rather than just claim a trade route, and they also deeply resent the Romans' having taken much grain and many hostages. There is, therefore, much to be gained if the Gauls are victorious.
As for the Romans, Galba's entrenchment is not finished nor do his troops have sufficient supplies to hold out for long, so when he learns of the Gallic treachery, he calls a council. Several of the officers suggest that they abandon their baggage and try to escape. The majority, though, want to wait for further moves by the Gauls. Their wish is soon granted. The enemy charges, hurling stones and javelins and at first the Romans are able to hold back the onslaught, but they begin to tire and their losses mount. The enemy soldiers, meanwhile, exchange fresh men for those who are weary and continue to remain on the offensive. The battle continues for six hours and Roman strength and weapons continue to dwindle. Enemy soldiers appear at the mouth of the trench and defeat seems at hand; indeed, it most certainly would have but for the intervention of Publius Sextius Baculus, senior centurion, and Gains Volusenus, military tribune, who plead with Galba that their only hope lies in one final and sudden charge. Galba agrees and calls the officers together, telling them to have all troops pause in their fighting, then gather their weapons, refresh themselves, and, on signal, burst forth.
The plan is stupendously successful. The enemy is taken by surprise and caught off-balance. The Romans surround them and slaughter a third of the 30,000 attackers; the rest flee to the hills. Galba wisely decides not to press his luck by pursuing them; his men are short of supplies. But he destroys the hamlet and returns to the province. His unit then winters in the territory of the Allobroges.
With the Belgae and the Seduni conquered and the Germans driven out, Caesar assumes Gaul is relatively at peace, but before he can get to Illyricum war once again kindles in Gaul. Publius Crassus has been wintering in the country of the Andes with the Seventh Legion and has sent some of his officers to neighboring states to get grain.. Titus Terrasidius to the Esubii, Marcus Trebius Gallus to the Curiosolites, and Quintus Velanius and Titus Sil ins to the Veneti.
The Veneti are a powerful seafaring nation, so powerful in fact that they control most of the navigation on the open sea beyond their coasts and immediately they imprison Silus and Velanius; they are quick to see that these men are ripe for hostages. The neighboring Gauls, impetuous as always, follow their example and hold Trebius and Terrasidius. They also swear by oath that they will cooperate with the Veneti in a common battle against Rome. Soon, other states join and the coast is united. Then, a deputation is sent to Crassus with an offer to trade the hostages for his officers.
Caesar is informed of these blackmail measures and orders that warships be built, that seamen be drafted from the province, and he sets off to join the army. The Veneti learn that the general is coming and, afraid, realize the extent of their offense — they have imprisoned important Roman officials. Thus they prepare for war, hopeful of victory only because they know the lay of the land and only because they think that there are but few harbors which the Romans will be able to use. They fortify their towns and assemble a fleet in Venetia, where they know Caesar intends to begin his campaign. As allies, they rely on the Osismi, the Lexovii, the Namnetes, the Ambiliati, the Morini, the Diablintes, and the Menapii; and, as added insurance, they send to Britain for more aid.
The campaign promises to be a very difficult one, but Caesar has several good reasons for pursuing it: it is outrageous that Roman officials have been taken prisoner and these nations have renewed the war after having made peace terms, and, worst of all, if the rebels aren't put down, then other Gallic tribes might also be stimulated to rebel. War is unavoidable. Caesar divides his army and spreads it to keep the remainder of the territory in check. He sends Titus Labienus forward with the cavalry to keep the Remi and the Belgae loyal and to hold back any Germans who might have been summoned by the Belgae. Publius Crassus is sent to Aquitania with twelve cohorts and cavalry, and Quintus Titurius Sabinus is dispatched with three legions to control the Venelli, the Curiosolites, and the Lexovii. Decimus Brutus the younger Caesar puts in charge of the fleet and he tells him to start for the country of the Veneti. Caesar, himself, departs with the land forces.
The Venetian strongholds are set on tongues of land which are unapproachable from land when the tide is in and unapproachable from the sea when the tide is out. This paralyzes the fighting, for whenever Caesar manages to erect devices to destroy the towns, the enemy counters by sailing away with all their supplies from the seaward side and going to another stronghold. The Romans then are forced to attempt attacks on the new fortress. These operations continue throughout the summer and, to add to the Romans' troubles, they find themselves impeded by bad weather and the lack of decent harbors. The Gallic ships are, of course, better suited for maneuvering in these waters. They are built higher and have flat bottoms so that they can be moved into the shallow ebb tides that can easily wreck the larger Roman ships; in addition, they are sturdy enough to withstand sea wind, waves, and storms and, though the Roman ships are faster, the Gallic ships are built so well that the Romans can neither ram them nor grapple them successfully.
After taking several of the towns, Caesar decides that the island battling is largely fruitless and getting him nowhere; each time the enemy is charged, it simply moves down the coast. He waits for his entire fleet to arrive before further moves are tried. When it does arrive it is sighted by the enemy, who approach with a force totaling 220 ships.
Brutus, in charge of the Roman fleet, is alarmed. The enemy has many more ships than he, and he knows that he cannot ram them, nor can he have his men hurl missiles at them because their decks are much higher than his. The enemy, on the other hand, can do a great deal of harm to his ships; they can maneuver closely and throw their weapons downward. The Romans, however, do have one device which they can use to advantage: sharp hooks on long poles, used to snag the lines supporting the Venetian rigging. When these lines are caught, the Romans row quickly ahead, the lines snap, and the sails and tackle fall upon the decks, immobilizing the enemy ships. The battle promises to be decisive and Caesar and his army station themselves on the hills to observe.
The Romans' sole asset proves wholly successful; when they destroy a ship's rigging, they surround it with two or three of their smaller vessels and send out boarding parties. The enemy is dismayed and realizes, finally, that it will be destroyed one ship at a time; hence, they decide to retreat, but the wind suddenly disappears and, from then on, the battle goes to the Romans: the trapped ships are all easily destroyed. Once again, Rome is victorious.
Now, because all the enemy's fighting men and ships have been assembled for this battle, the war against the Veneti and the coastal tribes is ended and the survivors come forward to surrender to Caesar; but, so that no other tribes will think of imprisoning Roman representatives in the future, the general is much more severe in his punishment than he usually is. Now he executes the captive senators and sells the men as slaves.
Meanwhile, Sabinus reaches the Venellian border. The chief of the tribe, Viridovix, has raised an army in readiness and has been joined by the Aulerci, Eburovices, and the Lexovii, as well as many desperadoes interested in the possibility of plunder; these men lie in wait two miles from Sabinus' camp. Sabinus continues to refuse to meet in combat the fighting groups Viridovix sends out each day, but his efforts at peace fail miserably. He soon finds himself held in contempt by the enemy and, in his own camp, he is the object of ridicule. Both sides think him a coward. Unfortunately, his troops do not realize that he is being only tactical: he doesn't wish to grapple with so large an enemy when he is not on favorable ground and without good opportunity. His plans are sparing many lives. But there is another element in Sabinus' strategy: when he is sure that the enemy is convinced of his fear, he can set his military machine into motion. His tactics call for patience, and he has an abundance.
He first sends out a Gaul who pretends to desert and enters the enemy camp, telling them that Caesar is in serious trouble with the Veneti and that Sabinus intends to lead his army out of camp secretly the following night. Sabinus' plot succeeds, and the Venelli, made bold by the Romans' apparent timidity, plus the report of the supposed deserter, their own lack of food, and an over-eagerness to believe gossip about the mighty Romans, decide to assault the empire's forces.
Sabinus' camp is on high ground and the enemy must charge up an entire mile of hill before reaching the Roman lines. Sabinus knows that any charge from the enemy must come quickly if they hope to be effective and if they hope to catch the Romans by surprise. Thus he is ready, and as the enemy arrives out of breath, he orders his troops to charge. The Romans have the advantage of being experienced men and, furthermore, they are experienced men charging downhill against tired attackers. The Gauls' ranks crumble and they trickle into hiding, but the Roman infantrymen seek out and kill them.
Sabinus and Caesar learn of each other's victory at the same time and the remaining rebel states surrender to Sabinus, for they are not willing to take up a fight which seems to have no purpose.
While all this warring is going on, Publius Crassus reaches Aquitania. In this territory — comprising a third of Gaul — a few years earlier, Lucius Valerius Praeconinus, had been killed, and proconsul Lucius Mallius escaped with a loss of all equipment. Thus Crassus is cautious. With considerable care, he gathers a large supply of grain, gets auxiliary forces from other areas, and then marches across the borders of the Sotiates. The Sotiates stand ready and their cavalry attacks the Roman army, but the Romans are as mighty as the reputation that accompanies them.
The Sotiates are especially eager to win this battle, for all Aquitania and their earlier victories have given them much confidence; the Romans, on the other hand, want to show how well they can fight without Caesar and his other legions. Thus the battle is fought at a high pitch and only flags when the enemy flees the field and Crassus is free to attack the stronghold. He brings up mantlets and towers and the enemy attempts a sortie, but the Roman troops prove so efficient that all tactics against them are unsuccessful. Finally, the Sotiates must ask Crassus to accept their surrender.
As often happens, treachery is yet afoot. While the surrender is being agreed upon and the Romans' attention is occupied, Adiatunnus, the enemy commander, attacks from another section of town with a group of 600 men, hoping for one last try at triumph. The defeat of this last show of rebellion is quick and Adiatunnus is soon on his knees, begging for surrender terms.
Crassus then leaves for the Vocates and Tarusates, and when these tribes hear how quickly Crassus has conquered Adiatunnus, they assemble a great number of troops and place them under their most experienced leaders; These leaders are somewhat different from those just encountered: they work in the Roman style, preparing entrenched camps and planning ways of cutting off Crassus' supplies. Crassus, though, knows that he is already outnumbered and that if he waits, the enemy will receive more troops. Even now, the enemy army can split and harass him and still maintain a large enough garrison to protect its camp. With the advice of his council, he decides to fight without delay. He brings out his troops at dawn, ready for the fight. But the enemy refuses to meet for battle. Roman-like, they want to wait until the Romans have run out of supplies and have to attempt an escape. Then, they think, they can easily harass the smaller force. Crassus understands this and permits his enthusiastic troops to attack. The Romans advance to the trenches and walls of the enemy camp and begin fighting, but Crassus keeps auxiliary troops, in whom he has little confidence, in service positions. The armies exchange missiles, then Crassus' cavalry reports that the enemy's rear has not been well fortified and is invitingly exposed. Crassus welcomes the news, and the cavalry and the Roman reserve units secretly make for the rear. In they charge, vigorously routing the enemy.
When the Romans in the front hear battle noises from behind, they are spurred with even greater vigor and the enemy is finally forced to retreat. It is chased by the Roman cavalry and three-quarters of the 50,000 enemy soldiers are killed.
Most of Aquitania hears of the victory and decides that surrender is necessary. But some distant tribes, knowing that winter is coming and that the Romans will not battle much longer, do not send hostages or agree to any surrender terms.
For the present, most of Gaul is peaceful, excepting the Morini and the Menapii, who have not come to terms. Caesar decides to have a last try before winter against these wily rebels, and so goes after them. The campaign, however, is not as quickly completed as he hoped. The enemy fights in forests and marshes and appears en masse only when the Romans are spread over a wide area. There are many skirmishes, and losses mount on both sides. In desperation, Caesar finally sets his troops to cutting down the forest in which the enemy hides itself. There they capture the enemy's cattle and some military equipment, but not the enemy itself; it moves deeper into the dark forest. Then cold winter weather descends upon the battle scene and Caesar is forced to withdraw. The decision is difficult, but the general, before leaving, accomplishes a last tactic: his troops destroy all crops and buildings in the enemy territory.
One of the sources of the Roman interest in Gaul was the lucrative trade carried on by the Romans, hence the importance of Galba's mission to open a route through the Alps. The Roman traders were losing a large part of their profits to the people who charged fees for passage over the Great St. Bernard Pass. Thus the Roman intervention.
When the Seduni and the Veragri attack Galba, note that he is in the worst of all possible situations — bad ground, limited supplies, and an unfinished camp he has nothing on which to rely except his own merit as a general and the device of surprise.
The Veneti, mentioned later in the book, are located on the southern coast of Brittany. They face an open sea and have developed a considerably different fleet than the Romans, who are used to mild Mediterranean waters. In fact, the Roman military forces are not naval at all; they are largely land fighters.
The offense of the coastal tribes is twofold: not only do they attempt to override Roman authority, but they take as prisoners ranking Roman officials on a diplomatic mission and, since the power of Rome often rested in a few men, this is a most serious act that must be punished.
Note that Caesar does not commit all his forces to a single campaign, even though it promises to be a difficult one. He knows there is always a chance that the rest of Gaul will take advantage of his being occupied elsewhere, so he sends a large part of his army to maintain order while he is away fighting.
There are two types of Roman ships mentioned in the sea battles against the Veneti and in the two British expeditions. The larger ships are primarily cargo carriers, with a deep draft below the waterline so that they are unable to advance closely toward shore. The men-of-war are small fighting ships, much more maneuverable.
Caesar never ignores the benefits of luck and he frequently mentions his indebtedness to it But he knows that luck is often most useful to those who are ready for it. Thus ships of his which have their sail-cutting devices are only completely successful when the wind drops and prevents the escape of the Venetian navy. Tactics and luck win this battle.
Concerning the Venelli and their allies, note that they outnumber Sabinus' forces and that he makes use of Caesar's gambit of appearing afraid so that the enemy becomes overconfident and careless. The enemy is both physically and psychologically injured by his charge. In addition, his military position on the hill contributes much to his success because the enemy is weakened by the long charge upward to reach the Roman lines.
The vassals mentioned in Adiatunnus' forces are a particularly effective fighting device. We see many times a tendency of troops to break and run when they find themselves in trouble, thus the vassals' promise to share their partners' fate makes running no solution to any difficulties, for even if one member of a pair should get away, he must die if his partner is not so lucky and, rather than risk that, they stay in battle and fight to the death.