Rome\'s most able general?

[Paullus Scipio]

Well, just as a 'for instance', take Cannae. The four Roman commanders seem to have commanded their own forces, and been posted thus, ( though there are some contradictions in the sources):-
On the right, commanding the Roman Cavalry, was the Consul Aemilius Paullus, who probably also commanded one legion and equivalent Aliies ( assuming the 10,000 camp guard came from his army, though I personally think the camp guard were 'Triarii' drawn from the whole army, in which case he would have commanded two legions plus Allies)
Aemilius Paullus dismounted and joined the infantry after the defeat of his Roman cavalry, and was found sitting on a rock, wounded and bleeding profusely toward the end of the battle by a Tribune called Lentulus. He offerred Paullus his horse ( which incidently indicates even Tribunes were normally mounted), but Paullus refused, and then Lentulus horse bolted as a party of Numidians came up ( according to Livy 22.49)

Next, commanding the centre came Marcus Minucius Rufus (Fabius' Master of Horse, and deputy to M. Atilius Regulus(who had been sent back to Rome, hence his deputy commanding). He was killed in the battle.The other commander of the centre was Cn. Servilius Geminus (Flaminius' original colleague).
Finally, commanding the left was the Consul Varro commanding his own two consular legions plus Allies, and on the left wing, the Allied cavalry.

This would seem to indicate that Master of Horse was a title for a Dictator's deputy, rather than necessarily an actual cavalry. commander.....