I don’t think that Hannival staged an orderly withdrawal “without trained troops.” I would think that after crossing the Alps 2 years earlier and rampaging up and down the Italian peninsula they would have been pretty well trained. After all, how was he going to add on new recruits? The amazing thing was maintaining discipline and morale with a large group of different tribal peoples with different languages. Anyone know how many languages Hannibal spoke? One can gain some sense of his difficulty by watching Lawrence of Arabia. You can see the hostility between the tribes at the beginning, and again at the end when the tribes are arguing over who was going to run what in Damascus. Fortunately for Lawrence, they all spoke Arabic and he was an accomplished linguist.
Regarding battle tactics, I was reminded of some research I did on a historical novel I hope to finish writing. I visited the site of the Battle of the Cowpens in South Carolina. This was a critical battle in bringing about the end of the American Revolution. I think that the southern role in fighting this war is seriously under recognized in teaching about that period. At any rate, there was aging General Daniel Morgan, facing nasty Banastre Tarleton (Blood Ban, killer of surrendered troops). He had a contingent of trained Colonial troops, but also a large number of “overmountain men” who had come from the west (Kentucky, Tennessee) to help fight the British. Morgan, knowing that these raw troops would not have the experience and discipline to hold the line placed them in front and said that after firing 2 or 3 shots they could retire to the rear and circle around to the sides. The British were then faced with the hardened Colonials. Over 600 British were captured and British losses over all were around 5 to 1. Here is a fascinating link, and while there you might also click the link to the crossing of the river Dan which ultimately led to the Yorktown defeat.
http://www.exploresouthernhistory.com/Cowpens1.html
Hannibal probably enjoyed a considerable advantage in troop quality. The Carthaginians relied heavily on mercenaries.His men were largely professionals, while Roman Army was still a short service citizen militia. Prior to Cannae, Hannibal had already inflicted two heavy losses on the Romans. The Romans kept raising new legions, but these men were probably not well trained.
As the Second Punic War dragged on, the Romans found themselves for the first time in possession of a large, long-service army. This was a big step in the professionalization of the Roman Army, which would be largely completed in the next century with the wars in Greece and Spain. In the early and middle Republic, the Roman Army was not yet the wonder of the world that it would become.
I visited Cowpens National Battlefield and visited with the historian. He had put green squares on maps of the states designating battles in the Revolution.
Turns out, there were more revolutionary battles in SC than any other state.