After Julius Caesar refused to comply with the ultimatum imposed on him by the Roman Senate, both sides took up arms and commenced military endeavors against each other. Thus was the start of the Great Roman Civil War.
As Caesar marched back from Gaul he won over the loyalty of many townships. Most of Caesar’s army was still in Gaul, but he had two legions with him and was recruiting more. Along the way back to Rome, he was able to recruit more soldiers from among the towns that appreciated him.
So, Pompey and his allies raised their armies and navies and then dispersed throughout Italia (modern: Italy).
Caesar then chased down Pompey and Pompey’s right hand man, Afranius. This chase led Caesar down to southern Italia (modern: Southern Italy).
At the sea town of Brundisium (modern: Brindisi, Italy), Caesar now with six legions—three veteran legions and three newly recruited legions—descended on Pompey who only had twenty-two cohorts, or about two legions with him. Pompey narrowly escaped Caesar by sea. Without a proper navy to pursue Pompey, Caesar then turned his attention to Afranius who was in command of much of Pompey’s army and had gone to Hispania (modern: Spain), a region loyal to Pompey.
Caesar took the overland route to Hispania sending some of his army ahead of him. The route, which took up Cisalpine Gaul (modern: Northern Italy) and Gallia Narbonensis (modern: French Riviera), was obstructed by Pompeian loyalists at the Roman town of Massilia (modern: Marseilles, France). Caesar’s forces successfully sieged its fortified walls and secured safe passage for the rest of his army.
Starting around March of 49 B.C. in Spain, Caesar and Afranius began a game of cat and mouse. Several skirmishes broke out between the two. Afranius continually got the better of Caesar’s forces. He was one of the great military commanders in Rome at the time and he employed tactics that Caesar had nearly no experience against. But in the end, Caesar got the best of Afranius. He began avoiding battles with Afranius even when conditions were favorable to him. Ultimately, Caesar was able to force Afranius’s surrender by essentially starving him out. Caesar did so with a course of offensive sallies at the flanks of Afranius’s army and keen offensive positioning on and along the River Ebro (modern: River Ebro), which effectively cut Afranius’ army off from the supplies and allied assistance that he had been receiving from the town of Ilerda (modern: Lleida, Catalonia, Spain).
This tactic is reminiscent of Vercingetorix’s strategy in the attempted rebellion in Gaul. Also, akin to Gallic strategy, Caesar put to great use his cavalry, a great part of which was actually comprised of Gallic horse and men.
Caesar commented on how armies naturally adopt the combat styles of their enemies after a while, especially if they stay on campaign in a foreign country for a long time. He noticed that Afranius’s army used a Spanish barbarian style of fighting in which the army rushes to a position then holds it by keeping loose rank and huddling in an unorganized mass. This style of opposition confused Caesar’s men early on in the campaign and resulted in some losses for Caesar’s army, because they were accustomed to meeting the enemy in a straight, horizontal line. Eventually, the strategy of using cavalry to harass the huddled enemy masses, cut them off from each other, and then circling them with infantry helped Caesar win battles. And a similar strategy on a larger scale, in which Caesar’s cavalry harassed Afranius’s camp while his legions surrounded the area so to cut Afranius off from allied supply routes and contingents allowing no chance to even forage for food, helped Caesar win his first campaign of the Civil War.
Afranius surrendered. His armies were disbanded, and he and his co-legate, or chief officer, Petreius, were given passage to leave Spain so long as they did not rejoin with Pompey’s forces. They broke that promise. But, Caesar attempted to conduct the war a level of civility. He, at least rhetorically, explained how he was reluctant to participate in it all, that Romans should not shed each other’s blood, and that he was only fighting in self-defense because his rights were being impinged and armies were raised against him.
Caesar left some of his troops back in Hispania to keep the region in allegiance to him. Unfortunately, he left a greedy, unscrupulous man in charge who, through a series of loans and taxes, robbed the inhabitants of several of Hispania’s towns. This posed a slight political problem later on, but eventually, with the officer’s expulsion and death–he tried to flee Spain with all the money he had stolen and was so eager to leave the country before being caught that he unwisely sailed down a river during a storm and was caught up in a surge between its outlet mouth and the inlet Mediterranean Sea and died with his stolen treasury.
Nevertheless, the defeat of Afranius closed the curtain on the Spanish theater of war though an encore would be given four years later. A brief military effort was led in 45 B.C. to hunt down some remnants of the losing faction who were fleeing to Hispania.
After the defeat of Afranius, Julius Caesar would return to Rome and briefly assume the title of dictator, essentially holding a position of martial law over Rome as it was technically in a state of war, for eleven days until he was elected consul. Then, he set off after Pompey who was rumored to be stationed in Sicily.