The Battle of Dyrrhachium – Caesar’s Greatest Risk

I’ve been waiting for five months to write this article.

Back in March, while writing the post on the Visigoth sack of Rome, I came upon an interesting story about a siege the Goths conducted during the time period of the sack of Rome. The author said “this siege was the largest in history next to Dyrrhachium.” Huh? I had never heard of Dyrrhachium. After going back to retrieve the reference I couldn’t find it. Thought it was in Gibbon, but no.

The reference mentioned Pompey against Caesar and I realized that this battle was alluded to but unnamed in the HBO Rome series. Pompey and Cicero took refuge in Greece where Caesar eventually attacked them. He won with an inferior force for reasons I never understood.

After Caesar crossed the Rubicon in 49 B.C, Pompey retreated from the city, crossed the Adriatic, and set up camp in Greece. Caesar, not in a hurry to chase him, decided to stabilize Spain first. He also lacked ships to transport his troops so he had to wait for them to be constructed. By the end of the year 49 B.C, a now impatient Caesar was anxious to attack his old triumvir friend. There were only enough ships for half the fleet but Caesar decided to proceed immediately even though the January storms would make passage difficult.

The following map shows the movements of the two armies.

Unknown to Caesar was the blockade set up by Pompey using his fleet under the command of Bibulus. Caesar was very fortunate in that he caught Bibulus off guard with a winter crossing and was able to reach the coast of Epirus (1). When Caesar sent the fleet back to retrieve the rest of the army, it was intercepted, blocked, and many ships were lost (2). Caesar now faced the prospect of fighting Pompey’s army of 45,000 with an army of 15,000. He attempted to treat with Pompey several times but was rebuffed. Resigned to doing battle, Caesar instructed the newly arrived Anthony to break the blockade and head north to meet him at Dyrrhachium (3,4). Pompey, hearing of Caesar’s movements, marched from Macedonia to try and get between Caesar and Anthony (5). Unsuccessful, he set up camp along the coastline south of Dyrrhachium.

Caesar, using his classic playbook, decided to build a circumvallation around the army of Pompey. The latter responded by constructing his own fortifications opposite Caesar. By the end of spring Pompey’s army was suffering from lack of fodder and needed to break out. Some Gallic horsemen defected to Pompey, telling him of a hole in Caesar’s line to the south. Pompey attacked there, forcing Caesar to retreat in order to save his remaining troops (6).

Caesar then took Gomphi by siege and then defeated Pompey for the final time at Pharsalus. Pompey escaped to Alexandria but was murdered by Ptolemy.

The map below shows the fortification detail.

Caesar's circumvallation was about 13 miles long.