Gladius thrust?

[Gaius Julius Caesar]

The Centurion you mentioned David, was one of Caesars most experienced, from the Xth I think, could be wrong, who re-enlisted to fight for Caesar in the Civil war! I believe it was in the final battle against Pompay Magnus! So it was effective even for the greenest of recruits against the most experienced! hock:

[M. Demetrius]

Yep, I reckon so. A gladius through the base of the neckbones will work just fine, no matter how tough the receiver is.

[Caius Fabius]

There are other theories about how Romans fought, such as space between each man, with a second man covering from slightly behind. Not locking shields, but having a fluid support line which could fill in gaps is another theory. SCA combat does not give us actual proof about how Romans fought, since when we fight SCA we fight with styles and techniques that include martial arts from modern times, and centuries of experimentation and learning. We also don't use missile weapons properly, as the Romans would have. If you have one line fighting, spaced apart slightly, a second line covering to step in or jump forward, and a third line hurling pila into the front ranks of an enemy, being resupplied by those behind them, it might be a whole different battle dynamic. This formation would still be screwed up in a forest or trees, but easier to control on broken ground.

The closed rank, (1st and 2nd line side by side) would be used against cavalry, or perhaps against an initial wild infantry charge, backed up by the rear ranks closing up, (remember probably 8 ranks deep in normal formation) while still using their pila, and the testudo used when subject to missile fire, are probably separate formations, not standard ones. The HBO Rome ballet was probably pure fantasy....

A trained man with a shield, in a loose line with plenty of room, can use his shield for protection, and use his sword, behind the shield, to damage his and his 'wing-men's' opponents. If you think of the Romans as being well trained to work together and fluid in their formations, you can see the advantage against well trained less fluid phalanxes or against warriors who did not train together, but might be excellent individual fighters. You can also see how a mad rush of lots of large men filled with blood-lust could break through the well-trained Romans, as happened several times in the written records.

I suspect the Individual Gladius combat was much different than any of the models we can imagine today, and certainly not the Hollywood Shield-wall that we see in so many visual interpretations.