On 10 January 49 BC, leading one legion, the Legio XIII Gemina, General Julius Caesar crossed the Rubicon River, the boundary between the Cisalpine Gaul province, to the north, and Italy proper, to the south, a legally-proscribed action forbidden to any army-leading general. The proscription protected the Roman Republic from a coup d'état ; thus, Caesar's military action began a civil war.
Caesar pursued Pompey to Brundisium, expecting restoration of their alliance of ten years prior; to wit, throughout the Great Roman Civil War's early stages, Caesar frequently proposed to Pompey that they, both generals, sheathe their swords. Pompey refused, legalistically arguing that Caesar was his subordinate and thus was obligated to cease campaigning and dismiss his armies before any negotiation. As the Senate's chosen commander, and with the backing of at least one of the current consuls, Pompey commanded legitimacy, whereas Caesar's military crossing of the Rubicon River frontier rendered him a de jure enemy of the Senate and People of Rome. Nevertheless, in March 49 BC, Pompey escaped Caesar at Brundisium, fleeing by sea to Epirus, in Roman Greece.
Caesar did not immediately give chase to Greece 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 that it wouldn't intervene during his campaign against Pompey. He then turned his full attention to Pompey. Having only built half the needed ships Caesar grew impatient and decided to gamble on sending half his army across, and to then have the ships travel back to Rome and transport the remainder. Travel across the Adriatic Sea to Greece would ordinarily be difficult, but was made more so given that it was winter and the sea was treacherous. In addition Pompey's fleet, commanded by Caesar's former junior consul Marcus Calpurnius Bibulus, lay between Caesar and Greece. 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 ships back to Italy, burning most of them. Bibulus died shortly after and command fell to Lucius Scribonius Libo.
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 broke Libo's blockade and managed to make it north of Caesar's position. 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.
Caesar was now in a dire position, holding a beachhead at Epirus with only half his army, no ability to supply his troops by sea, and limited local support, as the Greek cities were mostly loyal to Pompey. Caesar's only choice was to fortify his position, forage what supplies he could, and wait on his remaining army to attempt another crossing. Pompey by now had a massive international army; however, his troops were mostly untested raw recruits, while Caesar's troops were hardened veterans. Realizing Caesar's difficulty in keeping his troops supplied, Pompey decided to simply mirror Caesar's forces and let hunger do the fighting for him. Caesar began to despair and used every channel he could think of to pursue peace with Pompey. When this was rebuffed he made an attempt to cross back to Italy to collect his missing troops but was turned back by a storm. Finally, Marc Antony rallied the remaining forces in Italy, fought through the blockade and made the crossing, reinforcing Caesar's forces in both men and spirit. Now at full strength Caesar felt confident to take the fight to Pompey.
|Commanders and leaders|
|Gaius Julius Caesar|
|Gnaeus Pompeius Magnus|
|Approximately 22,000 legionaries (elements of 9 legions), 5,000–10,000 Auxiliaries and Allies, and Allied Cavalry of 1,800||Approximately 40,000–60,000 legionaries (12 legions), 4,200 Auxiliaries and Allies, and Allied Cavalry of 5,000–8,000|
Now you are about to see the view that the generals wish to have, and see the veterans romans of barbarians wars commanded by popular leaders against the auxiliaries troops with promises of Roman citizenship commanded by aristocrats senators, the fight will decide the fate of roman empires, and the world will not be the same before!