Flavius Scipio

generally the rank and file method was used in the more "civilized" armies and it helped to form soldiers into these units to fight more effectively rather than fighting as individuals like the beserkers. also when they charged the idea was to batter the first enemy line down with your shield and then thrust your swords into the second line. then you pull back a short way and continue, or that was the idea but if you could not pull back then you would try and keep fairly level with the men on either side of you to keep the line fairly straight, so as to fight more effectively as a unit.

I actually prefer the civil war battles, particularly the battle of Munda as it was the final battle of the civil war and it led to the end of the republic.

the Praeventores were more like the CIA in that they were spies and counter espionage inside roman territory, yet they could be moved into enemy territory to spy on enemies and carry out covert missions.

I chose early empire after the marius reforms and when the legions have converted from being 'republican' legions to imperial 'roman' legions, this was when they became loyal to one, the emperor man rather than their commander and the republic and it was now when their weapons and tactics were at their height.

Yet the praetorian guard were more of a hazard than a help to the empire, yet when their succesors, the Scholae units or their full name Schola Protectores Domestici, the "Protective Association of the Royal Escort" were instituted by Consantine the Great they were created purely to protect the emperor and were totally loyal and they were used in both the east and west yet they were eventually phased out in the west while in the east they remained the imperial guard. The eastern empires elite battlefield units were their cavalry, specifically the cavalry based on the eastern warriors. the western empire elites were the Imperial German Bodyguard and the Auxulia Palatina, while their spy's were the Praeventores which were in effect the succesors of the Arcani.

the empire that they conquered was eventually their downfall as, while they were conquering an empire they had their legions at full strength and many vetran units. when a sort of peace fell as in the romans were not conquering any more their legions one could say fell in to disrepair as the romans got complacent and even after the reforms of constatine where the army was split into the Limitanei (the border guards) and the Comitatenses (the mobile field army).More non romans were recruited into the army that in the end they were not fighting as a "roman" legion but rather fighting as a group of peoples under the roman banner when the west fell it was as a result of this dissection of the military and the failures of the emperors in trade, wars, management, etc... and the eastern empire survived simply because it had the well established cities and economy and because the eastern romans were adapting to eastern life rather than simply romanising everybody they could.

i believe the most pivotal battle would be the battle of Munda in the civil war between Caesar and the sons of Pompey, i mean this battle pretty much spelled the end of the republic and just imagine what could have happened if the pompeain forces had won. the whole of europe might have turned out differently as rome would still be a republic. Caesar himself told friends that he had fought many times for victory but Munda was the first time he fought for his life. this battle showed Caesar as a great improvisor on the battlefield as classic roman tactics would not work against other romans and it ended up in a bloody melee until caesars 10th turned the left of the pompeain forces and the retreat after that truned the battle into a rout with as many as 30,000 dying