The Via Julia now reaches into Illyria and Belgica. Britain finally becomes a province, but Caledonia remains a part of Britain rather than a separate province. Antony invades Armenia in Feb., and by May he defeats a large Armenian army under King Tigranes III at Tigranocerta, capturing the capital city in the process. Antony continues to pursue Tigranes for the rest of the year, struggling against Tigranes’ guerrilla tactics.
Caesar marches his army to the delta of the Euphrates by Jan. While the Parthians watch on, Caesar's army begins building a large navy of barges with which to sail around the Euphrates and Tigris via the ocean. Caesar continues to build barges for his army and by the end of Feb, Caesar loads his army onto the ships he has constructed and sails his army around the river delta to the other side of the Tigris into OTL modern day Iran, south of Susa. King Phraates is confused and immediately crosses the Tigris while Caesar's army sails toward the coast. Caesar leaves a messenger behind to race north and give Scipio a message to build a bridge across the Tigris and then burn it just like the previous ones and follow behind the Parthian army. Scipio immediately complies with Caesar's request. Caesar basically runs away from the Parthian army for six months, living off the land, engaging small groups of Parthian soldiers and always staying a step ahead of the main Parthian army led by Phraates. Scipio follows behind while waiting on word from Caesar. The Parthian army turns northwest towards their capital at Persepolis and waits for Caesar. Caesar now moves toward the Parthian capital as well. The two Roman armies converge on the Parthian king and fight the fierce, four-day Battle of Persepolis, followed by the less intense, but costly Second Battle of Persepolis (a battle popularized by the modern day movie, “Phraates’ Last Stand”) in August. On the 2nd day of the second battle, Phraates is killed in battle and his army surrenders. The capital falls shortly. The king's son, Phraates V and his mother, Musa take control of the Parthian government and vow to continue the fight from a new capital city in northeastern Parthia, Hecatompylos. Caesar remains at Persepolis for the rest of the year to rest his army after the massive battle, only occasionally engaging small, unorganized Parthian armies in the countryside around the city. Scipio manages to capture Susa by October, but is defeated at the Battle of Tabae by the Parthian satrap, Vordones because of his superior number of cavalry. Scipio retreats west to Ecbatana, which becomes his headquarters for conquering central Persia. Agrippa conquers the remainder of Asia and invades Armenia in December, well after Antony’s conquest of Tigranocerta.