Alright, time to get back in here and clear some things up.
What if the optimates / populares factions actually evolved into more formal political alliances (parties?) - could Rome have survived with a "balance of power" between the two groupings with the Army in between
That would likely only assure civil war. The shifting political alliances and backroom deals style of governance actually worked to
prevent civil war in my opinion. When allies started lining up firmly in two camps, bad things tended to happen.
Personally I'd go with Sextus Pompey emerging victorious over all others during the Second Triumverate. If he can use heavier ships, or counter Agrippas tactics, combined with taking on and winning against Lepidus, you have a strong Republican who could easily dominate the Mediterranean, and win the Civil War. He just needs to play Octavian and Antony against each other long enough to claim victory.
Assuming he stays a republican, you could see a reformed republic, and considering the chaos of the 2nd Triumverate, there is a very strong argument to do so.
It's a big if, though admittedly it's very possible. You have to give Pompey a reason to stay a republican. OTL he seemed very interested in getting a piece of the pie and working towards that end. His (very stupid I might add, since it gained him practically nothing and gained Octavian a lot) deal with the triumvirate essentially legitimizing his control of SIcily, Sardinia et Corsica, and technically the Peloponessus (though they never actually gave it to him) is highly suggestive of this. As is his remaining in contact with Marc Antony. If he defeats and kills Octavian (which he nearly did) I think it's far more likely he strikes a deal with Antony. Now whether he would use this to build up his own power and work towards some sort of Augustus or Caesar like rule over Rome or as a means to reform the republic a la Sulla is a toss up. I imagine though his father's heavy influence on him might be enough to make him stay true to republicanism and try to go the Sulla route.
1. Caesar was otl on Sullas proscription list, keep him on it.
That solves a symptom of the problem, not the problem itself.
2. A bonus would be if any of the other Boni, like lucullus works in politics a bit after his death, anything that keeps Pompey from tearing down the Sullan reforms to increase his own personal Dignitas.
Contrary to what many seem to think, the republic was actually getting along business as usual from the tearing down of the Sullan reforms until the crisis of 50-49. I can't really explain it here since it's been awhile since I touched Gruen's book, but he makes an extremely well researched and sourced case for that. The reforms really weren't too important in the grand scheme of things.
Caesar being defeated by Pompey might have worked for a while too. The question is whether Pompey after a victory would be satisfied with only First Man of Rome status or not. Was he truly wedded to the Republican cause/Boni of the Senate? Or was he more driven by rivalry with Caesar? If he ultimately went down the dictator route he has a pair of militarily competent enough sons to have a shot at making it heriditary.
There's nothing to suggest he would go down the dictator route. People seem to forget Pompey was for all intents and purposes in military and mostly political retirement by the time the crisis erupted. He didn't even bother anymore to go to his province he was technically commanding personally. He was too enthralled in his personal life by then to be too interested in any more military adventures. He was fine with weilding political power through others (given he was a terrible politician) and really just remaining on the sidelines by that point in time. Remember, his last major military campaign had been against Mithradates more than a decade ago.
Also, remember the people on his side and remember that Pompey wanted adoration more than he wanted power. He had the staunchest of staunch republicans on his side, and they commanded troops as well. They also weild immense influence in his camp, given it was their threat to simply take their troops and go somewhere else that prompted Pompey to finally cave in and give battle at Pharsalus. Even if he wanted to, which he certainly didn't, he wouldn't have been able to establish a dictatorship.
Granted, he's not going to reform the republic because he doesn't have the skill, knowledge, or political acumen (to say nothing of the will) to do so, but the republic will still remain. Since he seemed to always want to court Cicero, maybe he could get his advice for enacting some kind of reforms. One thing he does have, especially after saving the republicans asses, is the political power to push what Cicero suggests through if he wants to.
Given that Pompey hadn't shown much constitutional propriety in his earlier career, I doubt that he's the man to restore the constitution.
See above. Extra judicial commands were not new in the republic anyway, especially in times of crisis-which the couple years immediately following Sulla's death most certainly were. After that, the republic (and Pompey for the most part-the first triumvirate did not dominate roman politics as people think, judging by the fact they consistently failed to get their men elected during most of the period), continued mostly business as usual.
Well, he certainly had expertise to draw on among his political allies (e.g. Cicero). That's why I maintain that a reversed Pharsalus would at the very least give the Republic a chance to survive.
My thoughts too, which is why I think Pharsalus really was the last chance the Republic had.
It's not the
last chance. That really came after a couple decades of entrenched Augustan rule. It's the last best chance though.
I think 100 B.C. Is too late. The republic was dead before Caesar crossed the Rubicon, it just hadn't realized it yet. You can always give the republic more time, but you cannot prevent it from becoming an empire without destroying it.
Again, this is from hindsight and is thoroughly debunked by Gruen. I really need to purchase this book so I can start actually drawing some direct quotes from it and the like.