During the Civil Wars, the republicans had initially been led by Pompey, until the Battle of Pharsalus in 48 BC and Pompey’s death soon afterwards. However, in April 46 BC, Caesar‘s forces destroyed the Pompeian army at the Battle of Thapsus.
After this, military opposition to Caesar was confined to Hispania (the Iberian Peninsula, comprising modern Spain and Portugal). During the spring of 46 BC, two legions in Hispania Ulterior, largely formed by former Pompeian veterans enrolled in Caesar’s army, had declared themselves for Gnaeus Pompeius (son of Pompey the Great) and driven out Caesar’s proconsul. Soon they were joined by the remnants of the Pompeian army. These forces were commanded by the brothers Gnaeus Pompeius and Sextus (sons of Pompey) and by the talented general Titus Labienus, who had been one of the most trusted of Caesar’s generals during the Gallic Wars. Using the resources of the province they were able to raise an army of three legions. These were the two original veteran legions, and one additional legion recruited from Roman citizens and local inhabitants in Hispania. They took control of almost all Hispania Ulterior, including the important Roman colonies of Italica and Corduba (the capital of the province). Caesar’s generals Quintus Fabius Maximus and Quintus Pedius did not risk a battle and remained encamped at Obulco (present-day Porcuna), about 56 km east of Corduba, requesting help from Caesar.
Thus, Caesar was forced to move from Rome to Hispania to deal with the Pompeius brothers. He brought two trusted veteran legions (X Equestris and V Alaudae) and some newer legions (including III Gallica and VI Ferrata), but in the main was forced to rely on the recruits already present in Hispania. Caesar covered the 2,400 km from Rome to Obulco in less than one month, arriving in early December (he immediately wrote a short poem, Iter, describing this journey). Caesar had called for his great-nephew Octavian to join him, but due to his health Octavian was only able to reach him after the conclusion of the campaign.
Capitalizing on his surprise arrival Caesar was able to relieve the stronghold of Ulipia (a town which had remained loyal to him and had been unsuccessfully besieged by Gnaeus Pompeius) but was unable to take Corduba, which was defended by Sextus Pompeius. Under Labienus’ advice, Gnaeus Pompeius decided to avoid an open battle, and Caesar was forced to wage a winter campaign, while procuring food and shelter for his army. After a short siege, Caesar took the fortified city of Ategua; this was an important blow to the Pompeian confidence and morale, and some of the native allies started to desert to Caesar. Another skirmish near Soricaria on March 7 went in Caesar’s favor; many Romans in the Pompeian camp began planning to defect and Gnaeus Pompeius was forced to abandon his delaying tactics and offer battle.
The two armies met in the plains of Munda in southern Spain. The Pompeian army was situated on a gentle hill, less than 1.6 km from the walls of Munda, in a defensible position. Caesar led a total of eight legions (80 cohorts), with 8,000 horsemen, while Pompeius commanded thirteen legions, 6,000 light-infantrymen and about 6,000 horsemen. After an unsuccessful ploy designed to lure the Pompeians down the hill, Caesar ordered a frontal attack (with the watchword “Venus“, the goddess reputed to be his ancestor).
The fighting lasted for 8 hours without a clear advantage for either side, causing the generals to leave their commanding positions and join the ranks. As Caesar himself later said he had fought many times for victory, but at Munda he had to fight for his life. Caesar took command of his right wing, where his favorite Legio X Equestris was involved in heavy fighting. With Caesar’s inspiration the tenth legion began to push back Pompeius’ forces. Aware of the danger, Gnaeus Pompeius removed a legion from his own right wing to reinforce the threatened left wing. However, as soon as the Pompeian right wing was thus weakened, Caesar’s cavalry launched a decisive attack which turned the course of the battle. King Bogud of Mauretania and his cavalry, Caesar’s allies, attacked the rear of the Pompeian camp. Titus Labienus, commander of the Pompeian cavalry, saw this manoeuvre and moved some troops to intercept them.
The Pompeian army misinterpreted the situation. Already under heavy pressure on both the left (from Legio X) and right wings (the cavalry charge), they thought Labienus was retreating. The Pompeian legions broke their lines and fled in disorder. Although some were able to find refuge within the walls of Munda, many more were killed in the rout. At the end of the battle there were about 30,000 Pompeians dead on the field; losses on Caesar’s side were much lighter, only about 1,000. All thirteen standards of the Pompeian legions were captured, a sign of complete disbandment. Titus Labienus died on the field and was granted a burial by Caesar, while Gnaeus and Sextus Pompeius managed to escape from the battlefield.