Now this is the story all about how the legion got flipped-turned upside down, I’d like to make a blog, just sit right there, I’ll tell you how the army became supreme from a place called Roma
So here we have the Roman legion, the strongest and most organized army of their time…until the collapse that is. The legion was comprised of 4,000 t0 6,000 men. Cohorts two to ten were made of six centuries of eighty men; each century was commanded by a centurion. In a century, were ten contubernia, smaller squadrons of eight men, which provided more maneuverability on the battlefield. However, in the first cohort, which was the most elite, were five centuries of 160 men, with twenty contubernia in each century. 
But what made the legion so dominant was not its massive size, but its unity, the discipline, and their technology beyond their time. They were able to accept defeat, and take the best aspects of their enemies to adapt it as their own, but make it better. Just like the “85 Bears” they were brute force that trained and worked harder than all the rest. Their attacks from all angles, and the ability to overcome.
The Romans moved as a unit, they fought as one well oiled machine, where as the bands of Gauls and Britons fought recklessly and were poorly equipped and used guerrilla tactics.
Here we have a typical battle(Note that the black and green army men are the Romans, and only represent half a century)
Here are five contubernia being leg by a single centurion at the front
These miscellaneous figures represent the Gauls, whose fighting styles varied from tribe to tribe. Their battle formations were unorganized, they fought scattered, and were nowhere near as professional as the Romans, and also nowhere near as disciplined.