The Battle of Dyrrachium (or Dyrrhachium) on 10 July 48 BC was a battle during Caesar’s Civil War that took place near the city of Dyrrachium (in what is now Albania). It was fought between Julius Caesar and an army led by Gnaeus Pompey who had the backing of the majority of the Roman Senate. The battle was a victory for Pompey, albeit not a decisive one. The battle preceded the Battle of Pharsalus which was the decisive battle of the Civil War.
Caesar did not immediately give chase to Pompey and instead consolidated power in Rome and Italy. He had other problems as well; Pompey had left him with no ships to cross the Adriatic, and Spain had begun to mobilize against Caesar. After gathering the remainder of his forces from Transalpine Gaul he marched into Spain and subdued enough of the country so that it wouldn’t intervene during his campaign against Pompey. He then turned his full attention to Pompey.
Having only assembled half the needed ships, Caesar decided to take seven available legions across the Adriatic, and to then have the ships travel back to Brindisi and transport the remaining legions once they had arrived at Brindisi. Travel across the Adriatic Sea to Greece would ordinarily be tricky, but was made more so given that it was winter. However, this situation did assist Caesar because the Adriatic was treacherous enough to deter the war galleys of Pompey’s fleet, commanded by Caesar’s former co-consul Marcus Calpurnius Bibulus, at Corfu. As it was winter Bibulus was unprepared and Caesar was able to sail through the blockade easily and form a beachhead at Epirus with the first half of his army. Bibulus however was able to block Caesar’s attempt to sail his reinforcements stuck at Brindisi. Bibulus died while conducting this blockade and no overall naval commander was appointed by Pompey. At some point Lucius Scribonius Libo attempted to make the blockade more secure by seizing the island off Brindisi preventing Caesar’s reinforcements from sailing anywhere. However, Libo could not sustain this position because of a lack of water.
Caesar’s blunder had put him in the worst possible position any army could find itself in. His army had no way to resupply from Rome due to the naval blockade, he couldn’t resupply locally as Greece was pro-Pompey and closed their gates to Caesar, and his army was only at half strength. So dire was his situation that he made several attempts to discuss peace with Pompey but was refused at every channel. Realizing he was going to have to fight his way out, he attempted another winter blockade run back to Italy to lead his remaining forces to Greece. His luck was not with him and the rough seas and storms forced him back. However, his Master of the Horse Marc Antony fired up his troops and after several attempts evaded Libo’s blockade and managed to land at Nympheum (Shëngjin) with four more legions. It was now a race against time as both Caesar and Pompey rushed to meet Antony. Although Pompey reached Antony first Caesar was right on his heels and Pompey prudently moved his forces to Dyrrachium to prevent becoming caught between the two forces.
Dyrrachium was a strong defensive position for Pompey. His back was guarded by the sea, and at his front there were hills that commanded the immediate area. This made an assault on the position nearly impossible. Caesar instead decided to revisit his Gallic Wars play-book and ordered his engineers to build walls and fortifications to pin Pompey against the sea. Pompey responded with walls and fortifications of his own to prevent any further advance. Between these two fortifications a no man’s land was created which saw constant skirmishes with little or no gain—similar to the trench warfare of World War I. By mid-summer, Pompey had a fortunate stroke of luck and discovered the weakest point in Caesar’s wall: A section to the south of the lines hadn’t yet been completed and it was the only viable target for attack.
Pompey mounted an attack of six legions against Caesar’s line where it joined the sea and where the IX legion was stationed. Pompey also sent some auxiliaries and light infantry to attack by sea. Heavily outnumbering the Caesarian troops, the Pompeian troops broke through the weakened fortifications, causing the Ninth to pull back from the onslaught with heavy losses. Caesar swiftly reinforced the breach with 4,000 men, twelve cohorts under Mark Antony and then counterattacked, re-securing part of the wall and pushing Pompey’s disordered forces back. Although Caesar’s counterattack was initially successful, Pompey’s forces were simply too numerous. Some days earlier Pompey had occupied a small camp that had been abandoned by Caesar, and enlarged the defences. Caesar responded by sending 33 cohorts to attack this position. Although the attack was initially successful, the Caesarian troops were outnumbered 2-1 and Pompey’s troops fought hard. Pompey sent a large force of infantry and 3,000 cavalry to outflank Caesar’s right wing.
Caesar first ordered his troops on the right to stand firm, but then saw the danger of being outflanked. He ordered a retreat which soon became a panicked and disordered rout. The counterattack on Pompey’s camp disintegrated completely. At first Caesar personally tried to stem the retreat, but the fleeing troops did not stop until they reached their own camps. After the failure of the counterattack and considering the losses incurred, Caesar resolved to give up attempting to besiege Pompey and to change the entire strategy of the campaign.