It was now all-important for Caesar to secure practical irresponsibility by obtaining a military command. The senate, Gallic wars. in virtue of its constitutional prerogative, had assigned as the provincia of the consuls of 59 B.C. the supervision of roads and forests in Italy. Caesar secured the passing of a legislative enactment conferring upon himself the government of Cisalpine Gaul and Illyria for five years, and exacted from the terrorized senate the addition of Transalpine Gaul, where, as he well knew, a storm was brewing which threatened to sweep away Roman civilization beyond the Alps. The mutual jealousies of the Gallic tribes had enabled German invaders first to gain a foothold on the left bank of the Rhine, and then to obtain a predominant position in Central Gaul. In 60 B.C. the German king Ariovistus had defeated the Aedui, who were allies of Rome, and had wrested from the Sequani a large portion of their territory. Caesar must have seen that the Germans were preparing to dispute with Rome the mastery of Gaul; but it was necessary to gain time, and in 59 B.C. Ariovistus was inscribed on the roll of the friends of the Roman people. In 58 B.C. the Helvetii, a Celtic people inhabiting Switzerland, determined to migrate for the shores of the Atlantic and demanded a passage through Roman territory. According to Caesar's statement they numbered 368,000, and it was necessary at all hazards to save the Roman province from the invasion. Caesar had but one legion beyond the Alps. With this he marched to Geneva, destroyed the bridge over the Rhone, fortified the left bank of the river, and forced the Helvetii to follow the right bank. Hastening back to Italy he withdrew his three remaining legions from Aquileia, raised two more, and, crossing the Alps by forced marches, arrived in the neighbourhood of Lyons to find that three-fourths of the Helvetii had already crossed the Saône, marching westward. He destroyed their rearguard, the Tigurini, as it was about to cross, transported his army across the river in twenty-four hours, pursued the Helvetii in a northerly direction, and utterly defeated them at Bibracte (Mont Beuvray). Of the survivors a few were settled amongst the Aedui; the rest were sent back to Switzerland lest it should fall into German hands.
The Gallic chiefs now appealed to Caesar to deliver them from the actual or threatened tyranny of Ariovistus. He at once demanded a conference, which Ariovistus refused, and on hearing that fresh swarms were crossing the Rhine, marched with all haste to Vesontio (Besançon) and thence by way of Belfort into the plain of Alsace, where he gained a decisive victory over the Germans, of whom only a few (including Ariovistus) reached the right bank of the Rhine in safety. These successes roused natural alarm in the minds of the Belgae—a confederacy of tribes in the north-west of Gaul, whose civilization was less advanced than that of the Celtae of the centre—and in the spring of 57 B.C. Caesar determined to anticipate the offensive movement which they were understood to be preparing and marched northwards into the territory of the Remī (about Reims), who alone amongst their neighbours were friendly to Rome. He successfully checked the advance of the enemy at the passage of the Aisne (between Laon and Reims) and their ill-organized force melted away as he advanced. But the Nervii, and their neighbours further to the north-west, remained to be dealt with, and were
crushed only after a desperate struggle on the banks of the Sambre, in which Caesar was forced to expose his person in the mêlée. Finally, the Aduatuci (near Namur) were compelled to submit, and were punished for their subsequent treachery by being sold wholesale into slavery. In the meantime Caesar's lieutenant, P. Crassus, received the submission of the tribes of the north-east, so that by the close of the campaign almost the whole of Gaul—except the Aquitani in the south-west—acknowledged Roman suzerainty.
In 56 B.C., however, the Veneti of Brittany threw off the yoke and detained two of Crassus's officers as hostages. Caesar, who had been hastily summoned from Illyricum, crossed the Loire and invaded Brittany, but found that he could make no headway without destroying the powerful fleet of high, flat-bottomed boats like floating castles possessed by the Veneti. A fleet was hastily constructed in the estuary of the Loire, and placed under the command of Decimus Brutus. The decisive engagement was fought (probably) in the Gulf of Morbihan and the Romans gained the victory by cutting down the enemy's rigging with sickles attached to poles. As a punishment for their treachery, Caesar put to death the senate of the Veneti and sold their people into slavery. Meanwhile Sabinus was victorious on the northern coasts, and Crassus subdued the Aquitani. At the close of the season Caesar raided the territories of the Morini and Menapii in the extreme north-west.
In 55 B.C. certain German tribes, the Usipetes and Tencteri, crossed the lower Rhine, and invaded the modern Flanders. Expeditions to Britain Caesar at once marched to meet them, and, on the pretext that they had violated a truce, seized their leaders who had come to parley with him, and then surprised and practically destroyed their host. His enemies in Rome accused him of treachery, and Cato even proposed that he should be handed over to the Germans. Caesar meanwhile constructed his famous bridge over the Rhine in ten days, and made a demonstration of force on the right bank. In the remaining weeks of the summer he made his first expedition to Britain, and this was followed by a second crossing in 54 B.C. On the first occasion Caesar took with him only two legions, and effected little beyond a landing on the coast of Kent. The second expedition consisted of five legions and 2000 cavalry, and set out from the Portus Itius (Boulogne or Wissant; see T. Rice Holmes, Ancient Britain and the Invasions of Julius Caesar, 1907, later views in Classical Review, May 1909, and H.S. Jones, in Eng. Hist. Rev. xxiv., 1909, p. 115). Caesar now penetrated into Middlesex and crossed the Thames, but the British prince Cassivellaunus with his war-chariots harassed the Roman columns, and Caesar was compelled to return to Gaul after imposing a tribute which was never paid.
The next two years witnessed the final struggle of the Gauls for freedom. Just before the second crossing to Britain, Dumnorix, an Aeduan chief, had been detected in treasonable intrigues, and killed in an attempt to escape from Caesar's camp. At the close of the campaign Caesar distributed his legions over a somewhat wide extent of territory. Two of their camps were treacherously attacked. At Aduatuca (near Aix-la-Chapelle) a newly-raised legion was cut to pieces by the Eburones under Ambiorix, while Quintus Cicero was besieged in the neighbourhood of Namur and only just relieved in time by Caesar, who was obliged to winter in Gaul in order to check the spread of the rebellion. Indutiomarus, indeed, chief of the Treveri (about Trèves), revolted and attacked Labienus, but was defeated and killed. The campaign of 53 B.C. was marked by a second crossing of the Rhine and by the destruction of the Eburones, whose leader Ambiorix, however, escaped. In the autumn Caesar held a conference at Durocortorum (Reims), and Acco, a chief of the Senones, was convicted of treason and flogged to death.
Early in 52 B.C. some Roman traders were massacred at Cenabum (Orléans), and, on hearing the news, the Arverni revolted under Vercingetorix and were quickly joined by other tribes, especially the Bituriges, whose capital was Avaricum (Bourges). Caesar hastened back from Italy, slipped past Vercingetorix and reached Agedincum (Sens), the headquarters of his legions. Vercingetorix saw that Caesar could not be met in open battle, and determined to concentrate his forces in a few strong positions. Caesar first besieged and took Avaricum, whose occupants were massacred, and then invested Gergovia (near the Puy-de-Dôme), the capital of the Arverni, but suffered a severe repulse and was forced to raise the siege. Hearing that the Roman province was threatened, he marched westward, defeated Vercingetorix near Dijon and shut him up in Alesia (Mont-Auxois), which he surrounded with lines of circumvallation. An attempt at relief by Vercassivellaunus was defeated after a desperate struggle and Vercingetorix surrendered. The struggle was over except for some isolated operations in 51 B.C., ending with the siege and capture of Uxellodunum (Puy d'Issolu), whose defenders had their hands cut off. Caesar now reduced Gaul to the form of a province, fixing the tribute at 40,000,000 sesterces (£350,000), and dealing liberally with the conquered tribes, whose cantons were not broken up.
In the meantime his own position was becoming critical. In 56 B.C., at the conference of Luca (Lucca), Caesar, Pompey Break-up of the Coalition. and Crassus had renewed their agreement, and Caesar's command in Gaul, which would have expired on the 1st of March 54 B.C., was renewed, probably for five years, i.e. to the 1st of March 49 B.C., and it was enacted that the question of his successor should not be discussed until the 1st of March 50 B.C., by which time the provincial commands for 49 B.C. would have been assigned, so that Caesar would retain imperium, and thus immunity from persecution, until the end of 49 B.C. He was to be elected consul for 48 B.C., and, as the law prescribed a personal canvass, he was by special enactment dispensed from its provisions. But in 54 B.C. Julia, the daughter of Caesar and wife of Pompey, died, and in 53 B.C. Crassus was killed at Carrhae. Pompey now drifted apart from Caesar and became the champion of the senate. In 52 B.C. he passed a fresh law de jure magistratuum which cut away the ground beneath Caesar's feet by making it possible to provide a successor to the Gallic provinces before the close of 49 B.C., which meant that Caesar would become for some months a private person, and thus liable to be called to account for his unconstitutional acts. Caesar had no resource left but uncompromising obstruction, which he sustained by enormous bribes. His representative in 50 B.C., the tribune C. Scribonius Curio, served him well, and induced the lukewarm majority of the senate to refrain from extreme measures, insisting that Pompey, as well as Caesar, should resign the imperium. But all attempts at negotiation failed, and in January 49 B.C., martial law having been proclaimed on the proposal of the consuls, the tribunes Antony and Cassius fled to Caesar, who crossed the Rubicon (the frontier of Italy) with a single legion, exclaiming "Alea jacta est."
Pompey's available force consisted in two legions stationed in Campania, and eight, commanded by his lieutenants, Afranius The Civil war and Petreius, in Spain; both sides levied troops in Italy. Caesar was soon joined by two legions from Gaul and marched rapidly down the Adriatic coast, overtaking Pompey at Brundisium (Brindisi), but failing to prevent him from embarking with his troops for the East, where the prestige of his name was greatest. Hereupon Caesar (it is said) exclaimed "I am going to Spain to fight an army without a general, and thence to the East to fight a general without an army." He carried out the first part of this programme with marvellous rapidity. He reached Ilerda (Lerida) on the 23rd of June and, after extricating his army from a perilous situation, outmanœuvred Pompey's lieutenants and received their submission on the 2nd of August. Returning to Rome, he held the dictatorship for eleven days, was elected consul for 48 B.C., and set sail for Epirus at Brundisium on the 4th of January. He attempted to invest Pompey's lines at Dyrrhachium (Durazzo), though his opponent's force was double that of his own, and was defeated with considerable loss. He now marched eastwards, in order if possible to intercept the reinforcements which Pompeys father-in-law, Scipio, was bringing up; but Pompey
was able to effect a junction with this force and descended into the plain of Thessaly, where at the battle of Pharsalus he was decisively defeated and fled to Egypt, pursued by Caesar, who learnt of his rival's murder on landing at Alexandria. Here he remained for nine months, fascinated (if the story be true) by Cleopatra, and almost lost his life in an émeute. In June 47 B.C. he proceeded to the East and Asia Minor, where he "came, saw and conquered" Pharnaces, son of Mithradates the Great, at Zela. Returning to Italy, he quelled a mutiny of the legions (including the faithful Tenth) in Campania, and crossed to Africa, where a republican army of fourteen legions under Scipio was cut to pieces at Thapsus (6th of April 46 B.C.). Here most of the republican leaders were killed and Cato committed suicide. On the 26th to 29th July Caesar celebrated a fourfold triumph and received the dictatorship for ten years. In November, however, he was obliged to sail for Spain, where the sons of Pompey still held out. On the 17th of March 45 B.C. they were crushed at Munda. Caesar returned to Rome in September, and six months later (15th of March 44 B.C.) was murdered in the senate house at the foot of Pompey's statue.