For a "History Professor" you get way to much of it wrong.
What did they accomplish? Caesar followed in the footsteps of Marius and turned military brilliance into political idiocy and destroyed the Roman Republic. Hitler? Well, since he apparently had never heard of Napolean or the Schlieffen Plan, did the same damn thing and got identical results. Machiavelli? Well he was a joke as a military commander. His attempts to modernize the army of Venice were on a par with Rumsfeld and McNamara. He did write a pretty good book though. Gee, what is he remembered for........ 
FQ13 who will close with a quote from Keynes " Practical men, who believe themselves to be quite exempt from any intellectual influences, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back". 
First off, The Republic was fu#ked before Julius showed up or they would not have been so violently factionalized.
Second, JC's crossing of the Rubicon under arms was a self defense action in reply to spurious charges leveled against him by the thoroughly corrupted Senate.
Lastly, while the Republic may have disappeared, the Empire lasted in one form or another till the dissolution of the "Holy Roman Empire" in the late 1800's.
Not a bad legacy if you ask me.
I won't waste my time correcting the rest of your post, Knowledge is wasted on some one who actually pays attention to an idiot like John Maynard Keynes, who's contribution to society was "Deficit spending".
I've said it before, You seem like a smart guy, why do you always reference a bunch of socialist dumb azzes,
Unless.........