The Battle of Munda (17 March 45 B.C.), in southern Hispania, was the final battle of Caesar's civil war against the Roman Republic, and against the leaders of the Optimate. With the military victory at Munda, and the deaths of Titus Labienus and Gnaeus Pompeius (eldest son of Pompey), Caesar was politically able to return in triumph to Rome, and then govern as the elected Roman dictator. Subsequently, the assassination of Julius Caesar began the Republican decline that led to the Roman Empire, initiated with the reign of the Roman Emperor Augustus.
The conservative 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 remains 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 Oculbo, about 35 miles (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 1,500 miles (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 one mile (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. Many of the Republican soldiers had already surrendered to Caesar in previous campaigns and had then deserted his army to rejoin Pompeius: they would fight with desperation, fearing that they would not be pardoned a second time (indeed Caesar had executed prisoners at his last major victory, at Thapsus). 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 Mauritania 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.
What is clear is that the Munda conflict was no mop-up operation. Tens of thousands of Romans died at Munda, where Caesar fought for his life among the ranks. About one month after defeat, Gnaeus was captured and executed. His brother Sextus survived to initiate another rebellion, on Sicily, where he was finally defeated by Marcus Agrippa and executed in Asia in 35 BC by Mark Antony, ten years after Munda.
Caesar left his legate Quintus Fabius Maximus to besiege Munda and moved to pacify the province. Corduba surrendered: men in arms present in the town (mostly armed slaves) were executed and the city was forced to pay a heavy indemnity. The city of Munda held out for some time, but, after an unsuccessful attempt to break the siege, surrendered, with 14,000 prisoners taken. Gaius Didius, a naval commander loyal to Caesar, hunted down most of the Pompeian ships. Gnaeus Pompeius looked for refuge on land, but was soon taken and executed.
Although Sextus Pompeius remained at large, after Munda there were no more conservative armies challenging Caesar’s dominion. Upon his return to Rome, according to Plutarch, the "triumph which he celebrated for this victory displeased the Romans beyond any thing. For he had not defeated foreign generals, or barbarian kings, but had destroyed the children and family of one of the greatest men of Rome." Caesar was made dictator for life, though his success was short-lived; Caesar was murdered on March 15 of the following year (44 BC) by the next generation of statesmen, led by Brutus and Cassius.
The exact location of Munda has remained a mystery for a long time. Some Spanish historians asserted that Munda was the Roman name for modern-day Ronda, where the battle of Munda may have been fought. Other early researchers localized the battle in various other places, e.g. near Monda or Montilla, the latter having been proposed on the basis of on an earlier localization attempt that was only meant to honor a member of the French royal house, who was born in Montilla. It is a matter of civic pride in Montilla that the Battle of Munda was (according to them) fought nearby, and at the outset of Hispanist Prosper Mérimée's novella Carmen, source of George Bizet's opera, the narrator clearly states that his research indicates that Munda was near Montilla. (No reference to either Munda or Montilla is found in Bizet's opera.) Other experts have asserted that Munda was fought just outside Osuna, in the province of Seville. This was corroborated by ancient slingshot bullets that were excavated near La Lantejuela, halfway between Osuna and Écija. The theory is further supported by ancient inscriptions found in Écija and Osuna that honor the town of Astigi (Écija) for standing firmly on Caesar's side during the battle. Therefore, the Battle of Munda probably took place on the Cerro de las Balas and the Llanos del Aguila near La Lantejuela. However, the exact location of the battle still remains controversial among archaeologists.