All right, so, per my plan to write six months of this TL each day, here's the next three months of 43 BC, as winter lightens into spring!
April
Caesar, having made record time crossing the Republic's territories, reaches Byzantium (or, more properly, Byzantion) on April 19th, where he is met by a flushed Armenian soldier named Safandasat. (Many scholars would later claim that this was a Latinization of the Armenian name Xavandisat.) Safandasat, or Xavandisat, informs him in hushed tones that Armenia has been defeated by the Parthians, and that the King has been forced to fight alongside Pacorus with 2,000 Armenians, or face execution. Moreover, he says, the Parthian army has made Arshamshat, in northern Armenia, their base and are launching scorched-earth raids into Roman Cappadocia. The local garrisons are powerless to stop them, being too few in number and too ill-trained to make much of an impact. Caesar, learning these things, becomes enraged and ordered a fleet gathered up at the port of Byzantion at once. They will sail to Lesser Armenia, in Roman Pontus, then launch a daring attack to Tigranakert, which will force the Parthian army to withdraw from Arshamashat and fight Caesar on his own terms. So confident is he of his plans, that he dismisses Xavandisat before he could inform him of the total numbers of the Parthians. And thus has Caesar made the first great mistake of the Eastern War.
Back in Rome, Marc Anthony is becoming seriously considered over his lack of mention in Caesar's will, and the ramifications of the will altogether. A dual dictatorship would mean the end of Republican Rome, and the beginning of an Empire: something no common Roman wants to see. Anthony and Brutus decide against consulting the remnants of the Senate; they are mostly filled with Caesar's puppets now, and would likely cause problems for the two. Anthony instead begins to raise an army in northern Italia, ostensibly for "rebel hunting". Octavian, undergoing a military education in Apollonia, nonetheless eyes these developments with extreme suspicion. Knowing of Brutus' opinions, he has reason to suspect the Senator's motives, and Anthony's as well. Thus, he sends a letter containing his suspicions to the one person who he believes he may be able to trust; his father's mistress, Cleopatra VII Philopater, pharaoh of Egypt.
May
On May 5th, Caesar's army lands in Roman Pontus, where he immediately begins recruiting the local garrisons for service. As such, by the time he reaches the Armenian border, his force has increased to 10,000. He invades at the Roman border town of Melitene, where he cuts a wide swath through the Kingdom, around heavily-defended Arshamshat. Pacorus, holed up in the city, is perfectly content to wait for Caesar to finish raging; Arshamshat has plenty of food, and there are several wells within the city. The Parthians can wait. However, Tigranes II, the King of Armenia, is furious at Pacorus' apathy, and threatens to leave the city with his army if Pacorus will not attack Caesar's army. The Shahanshah famously replies, "A fool are you, to think that I would value you and your soldiers more than the poorest Parthian." Nonetheless, he agrees to attack the Romans before they reach Tigranakert, Tigranes' capital. On May 12th, the Parthians leave Arshamshat, marching for the lake of Van, just a few miles east of Tigranakert, where Caesar is rumored to be. And on May 20th, the two armies meet, after several days of challenging each other to be the first to strike.
The Parthians begin the battle by covering the field with arrows. The Romans avoid most of these, using their revolutionary "turtle" small-unit formation. Pacorus orders a cavalry charge into the Roman ranks, using the famed Parthian cataphracts. At first, when the cataphracts strike the massed ranks of Romans, it seems as though the Romans have broken; the legionnaires turn and run, seeming to retreat. The cataphracts and Armenian irregulars pursue, already smelling easy victory. However, they have been tricked. In the reeds of Lake Van wait the 2,000 equites that have accompanied the army, commanded by Lepidus. After the cataphracts ride past, the equites burst from the reeds and charge into the back of the cavalry force; while in front, the Roman infantry suddenly turns and hardens into a powerful defensive line. The cataphracts, unfortunately for the Romans, prove to be a much more powerful and courageous force than Caesar foresaw. After much bloodshed and hand-to-hand fighting near the lake, Pacorus and a group of his cataphracts, around 300, bust through the legionnaires lines, and proceed to hammer the Roman infantry in a series of short cavalry charges. The rest of the Parthians, however, still trapped within the two walls, are unceremoniously slaughtered by Lepidus' cavalry. The horse archers, however, pepper the Roman cavalry with arrows, forcing them to withdraw. After several hours of this, Pacorus asks for a ceasefire. Caesar and Pacorus parley in a beautifully decorated tent in the center of the battlefield, while their troops are sweating in the desert sun. After several more hours, they finally emerge, with an agreement; Rome will be given most of western Armenia, up to the Dsopk river. Parthia will be given most of southeastern Armenia, up to Lake Urmya. The rest will remain as an independent, neutral Armenian Kingdom, to act as a buffer state between the two massive powers. Caesar is unsatisfied by the results, as none of Parthia had been taken, whilst 4,392 Roman lives had been lost in the reconquest of Armenia. Pacorus, while he has lost many Parthians, is happy with the results. There is now a neutral buffer state between him and the massively powerful Roman Empire; he has added more territory to Parthia itself; and he has humiliated Caesar with these terms. Tigranes II, on the other hand, is utterly furious with both powers; only 429 Armenians remain, out of the 2,000 that originally went to battle. He returns to Tigranakert hungering for revenge. A third thing happens on this day; as Caesar and his army leave Armenia, marching southwest to the newest portion of Rome, Caesar's horse is frightened by a squealing pig, and bucks him. Caesar is thrown to the ground, where he is knocked unconscious by the blow. Though he wakes up mere minutes later, his soldiers regard this as an inauspicious omen. And indeed, only three days later, on May 23rd, he falls mysteriously ill at Antioch, and dies on the sea-journey back to Rome. Lepidus quickly takes command of the army, and has the fleet land at Rhodes, where the army remains, under command of the Armenian soldier Safandasat. He himself sets sail for Rome.
June
Upon reaching Rome, Lepidus quietly informs Brutus, Marc Anthony, and the Senate of Caesar's death. He then reads to them Caesar's will, of which he has made a second copy. The Senate votes, with 10 dissensions, to honor the dictator's will, upon which Brutus stands and makes an impromptu speech on the glory of Roman republicanism and how it must be preserved. While this sways a few Senators, it is not enough to repute the will. After this, Brutus storms out, accompanied by Marc Anthony. Anthony prepares his newly-raised army for war, as news of the will and Brutus' speech spreads like wildfire throughout the Republic. In Apollonia, Octavian learns of the will, and quickly takes command of the three legions attached to the military school. Crossing the Illyrian channel, he begins marching south to take triumphal control of his Empire, while Marc Anthony prepares to meet him at the Rubicon. Meanwhile in Egypt, Cleopatra, though grieving, is overjoyed by the fact that her son will become Emperor of an Eastern Roman Empire. She immediately declares Alexandria the capital of the new Romano-Kemetic* Empire, and has her son crowned there.
*Kemet is the Ancient Egyptian word for Egypt; the Romano-Kemetic Empire will consist of the Bospurus, Syria, Northern Africa, Egypt, the Levant, the future Holy land....basically all of the Eastern Roman provinces beyond the Hellespont, along with North Africa.
Thoughts?