Hmmm... perhaps I am mistaken on Cynoscephalae, although I know I've read that Philip ordered his right wing to use swords instead of pikes. I do know the story of the raised pikes - a sign of Macedonian surrender, which the Romans either did not know or did not care about, leading to the slaughter of the Macedonians - but that could be referring to the disorganized left wing of the army (which was still using its pikes) or you can argue that it's like a "white flag"; I mean, not everybody carries a white flag with them to surrender with, but if the enemy is bearing down on you you'll rip out your own :furious3: underwear to make yourself a flag. Macedonians could well have just picked up any pike to show their surrender - wouldn't you if you saw the Romans bearing down upon you?
You and Livy are of course both correct that an army struck in its rear was in big trouble, especially a Macedonian phalanx - but you are incorrect, I believe, on it being simple for the Macedonians to turn to face the Romans, which they didn't. They didn't because all Philip told them to do was drop their pikes - he didn't tell them to break formation. The Macedonian right-wing at Cynoscephalae was still in a phalanx formation, only without the pikes, because 1) reorganizing would take too much time 2) the Macedonians, who were neither as well trained nor as well-armed as the Romans, would have inevitably had a "pack" mentality" and 3) Philip just needed to push the Romans off the hill, whereupon they would presumably break. When they were ordered to use swords, Philip was essentially just making sure that his phalangites used their swords on his and not the Romans' terms. Remember too that Philip thickened his right-wing, which would have added weight that was valuable for pushing the Romans off the hill but also made the already cumbersome Macedonian line even more bloated, allowing for the Romans to easily exploit their rear. Consider what happened at Cannae; the Romans increased the depth of their formations in an attempt to break through Hannibal's center, which they very nearly did - until they were hit in their flanks by the Libyans and Hannibal's cavalry. Had the Romans tried an organized breakout they probably would have succeeded; instead, the Romans naturally panicked and any semblance of battle order was lost.
Your comments on Pydna seem only to support me. As I said before, a phalanx was very tough to handle when it had an organized advance going - but this advance was very difficult to maintain and once momentum was lost, it could not be regained. So it was at Pydna; the Macedonians advance well, pushing the Romans back to the foothills. But then terrain, fatigue, stubborn Romans, etc. all combined to ruin that perfect advance, which the Romans quickly capitalized upon. To me it seems highly doubtful that the Macedonians could have halted to reform their lines, even if they wanted to, for two reasons: 1) the Romans were on the run, why stop? and 2) it has been repeatedly pointed out before that once a phalanx was committed, it was extremely difficult to get it to do anything else besides "keep moving forward". To me it implies a level of command-and-control and discipline that the Macedonians (at this point anyway) were not capable of.
Again, I think we're basically saying the same thing but in two different ways. The phalanx, in a perfect situation, should theoretically be able to steamroll legionnaires before it. The fact that this didn't happen shows that the phalanx rather quickly became disrupted and bogged down, again for reasons listed previously (terrain, fatigue, discipline, stubborn Romans). You said it yourself: "The phalanx itself could not finish the battles. It could kill and push but not crush the enemy." And that's exactly what would happen - the phalanx would kill and push, but simply could not maintain that for long enough so as to end the battle; it took outside forces, like the cavalry you mentioned, to do that. This was the ultimate problem of the late Macedonian armies - they relied too much on the phalanx to do too much, rather than the phalanx-and-cavalry combination perfected by Alexander. Had Philip, at Cynoscephelae, ordered cavalry to hit the flank of the main Roman body facing his right wing, he might very well have broken the Romans and carried the day; the Romans were downhill, seeming unable to make any headway against the sheer mass of phalangites before them, and the majority of them could not have had any idea of what was happening on their right (Philip's left). Philip effectively snatched defeat from the jaws of victory.
That the Celts were unable to penetrate the forest of pikes simply shows that they were different from the Romans. First, the vast majority of the Celts would have been much less-well armored than their Roman counterparts, and quite a few would not even have had shields - especially not great big shields, which the Romans happened to enjoy. Secondly (and this is a two-parter :2thumbsup: ), though there is little doubt in my mind that the Celts were individually better swordsmen than the Romans, 1) not all Celts were swordsmen; many were spearmen, and would have posed far less of a threat if they managed to penetrate the phalanx; and 2) the Celts individual nature would have made it less likely that they would penetrate the pike wall. They would have been more likely to try it, but they would have been less likely to try it in an organized fashion. Like you mentioned earlier, the Romans would have had centurions etc. saying "Right lads, split into 3's and look for gaps in the pikes, and when you find one, move into it!" (except that they would have said it in Latin). The Celts would have been more likely to go "YAARRRRRRR!" and run screaming into the phalanx - and likely right into the head of a pike. Imagine it as finding a needle in a haystack - or, better yet, a hay in a needlestack. A Celt is going to dive into the hay/needlestack; now he might find the needle/hay, but he probably won't (and he'll probably be cut really really badly from all those lovely needles). The Romans, on the other hand, would have divided the pile into sections and given a pile to each legionnaire or group of them, whereupon he/they would begin taking apart the pile until he find his needle (or his hay). It'll take him/them longer than it might take the Celt, but he/they are also more likely to succeed.
As an aside: Have you ever considered Roman reenacting? We always need smart people to help us out (as opposed to, say, being one of those people who asks if we're Greeks, or insists that the Romans didn't have metal). You don't happen to be anywhere near Colorado, do you :beam: ?