I think the idea that Hannibal's troops were poorly trained and the Roman troops were well trained is the flaw in your understanding there. Hannibal's army contained several highly experienced contingents; it would be foolish to say that the tactics had nothing to do with Cannae, because they absolutely were decisive in the outcome, but Hannibal's men were definitely veterans of several previous battles if nothing else. His actual plan for Cannae relied on the individual superiority of his (better trained) cavalry and on the ability of his African troops to wheel in for the flanking attack; accounts say that his Libyans at least were armed and equipped in an almost identical way to the Romans.Not really , Hannibal is a classic example at Cannae
More to the point, the Roman army at Cannae was twice the size of their usual army (eight legions instead of four) which means by definition that at least half the army was newly raised; given the heavy casualties already inflicted on the Romans it's quite possible that most of their army was. They'd certainly spent less time as formed organizations than Hannibal's men had, since those had essentially not changed as a body since before Trebia.
The Senate determined to bring eight legions into the field, which had never been done at Rome before, each legion consisting of five thousand men besides allies. ...Most of their wars are decided by one consul and two legions, with their quota of allies; and they rarely employ all four at one time and on one service. But on this occasion, so great was the alarm and terror of what would happen, they resolved to bring not only four but eight legions into the field.
Volunteerism versus professionalism isn't actually a dichotomy; British troops at the time were volunteers after all. But it's worth noticing that the Patriots (1) spent a lot of time training - see Valley Forge for example - and (2) were glad to get help from the professional French.You could also debate that the War of independence was won by volunteer troops vs professional troops.
Heck if you look at the Union army at Gettysburg and take note of the New York regiments anything in 70s was considered a veteran regiment , So you find the 124th NY formed in Sep 1862 giving the 1st Texas a bloody nose on the 2nd day due to fantastic leadership of its senior officers.
I mean, you're arguing here that a regiment that's been through two battles (Fredericksburg and Chancellorsville) qualifies as non-veteran. I'll note by the way that the 1st Texas is considered to have performed well at Gettysburg owing to having achieved a lot fighting with smaller numbers than the enemy, and it took its objectives.
Iverson's men were lined up like on parade when they were slaughtered the lack of leadership and the fact that no skirmishers were sent out meant that all the training and drill in world could not prevent them getting decimated.
Oh, I disagree on so many levels in the idea that all the training and drill in the world could not have saved them... if nothing else, these aspects of training and/or drill could have helped:
- Training in musketry, to win the exchange of fire.
- Drill sufficient to allow a formation to manoeuvre under fire, which would have allowed them to close in for a bayonet charge (for example).
- Drill which would enforce the idea that you always advance with skirmishers first.
But the thing is, these two Gettysburg examples are focusing in on very specific cases. The idea that training and drill makes soldiers better does not automatically mean that the better trained formation always wins, what it means is that training and drill gives an advantage - and often a major one. Which is why armies put fresh troops who haven't had time for much training or drill up against the enemy in desperate circumstances, not as a matter of course.
Note by the way that nothing about having better trained troops prevents you from also using better tactics.