IIRC, I've read some contradictory things so I would appreciate it if someone could set me straight:
When close fighting other infantry - after the pila have been thrown - would most Roman legionnaires be holding in their non-shield hand a gladius or some sort of spear?
How far would soldiers be standing from each other in close fighting? Close enough to form a shield wall, or was there some space between each man and the man to his right or left?
When fending off a cavalry charge, would most Roman legionnaires use their pilum as a spear, or would they throw it? Was there another weapon they had that they would use as a spear to fend off cavalry charges?
If it depends on the time period, I'd like to know about (a) during the third century BC, (b) after the Marian reforms, and (c) early fourth century.
Thank you
Hi, as you asked three separate questions, I split my answer into three parts, I can go in depth on these more if you have further questions.
1st question: Legionaries carried two pilum, a longer one that would be thrown before the charge, and a heavier one thrown during the charge, right before contact. A legionary couldn't hold anything in his left hand as it would be holding his scutum by the central boss grip. 2nd question: soldiers would stand with a gap between, this allowed them to fully swing their gladius without fear of striking an ally, and allowing them to maneuver their shield too. This distance would have between four and five feet. 3rd question: the romans would brace themselves using their shields and lower their javelins, using them as an improvised spear in the event of a cavalry charge. Horses will not charge into what they perceive as a solid object, so the wall of shields, if properly formed, could fend off most cavalry charges.
The Roman Legionary received fairly consistent training throughout the empire, so this would be largely applicable in all three time periods you listed. However, in the late empire, Legionaries began carrying Plumbata darts on the inside of their shields, which were small enough to be carried even during hand to hand combat, unlike the Pilum javelin.
Edit: adding some sources for further reading Roman battle tactics 109-BC to 313 AD. Roman battle tactics 390-110 BC These are two great, shorter reads that should cover all the eras you've shown an interest in.