According to Livy the Romans won a significant battlefield victory in Samnium during 322 BC (Second Samnite War), at an unnamed location, and with either a specially appointed Dictator or the consuls for the year in command.
The problem in identifying the commander pre-dated Livy's work. All of the records available to him agreed that A. Cornelius Arvina was appointed as Dictator during 322 BC, but they don't agree on the reason. In some sources he was appointed by the consuls Q. Fabius Rullianus (the victor of Imbrinium three years earlier) and L. Fulvius Curvus, when they learnt that the Samnites had raised a large army reinforced with mercenary troops. Arvina then commanded the army in Samnium. In the alternative tradition he was appointed Dictator in Rome after the praetor L. Plautius fell ill. His only duty was to officially start the chariot races for the year, and then he resigned. This second tradition was supported by the Fasti Capitolini, which credit the consuls with a triumph in this year,
Whoever was in command didn't make a particularly good job of the advance into Samnium, choosing a bad place for one of their camps. The Samnites took advantage of this mistake, and late in the evening built their own camp very close to the Roman position.
This must have put the Romans in a very vulnerable position, for that night their commander decided to retreat. The Samnite cavalry followed the retreating Romans, but didn't attack them until dawn. The Romans were then caught crossing difficult ground, and the Samnite infantry was able to catch up with the retreating army. The Roman commander decided to build a new camp where the army stood, but the Samnite cavalry prevented the Romans from gathering timber. The Romans were forced to turn and fight.
The fighting began at about nine in the morning, and continued without any advantage to either side until two in the afternoon. About then a party of Samnite cavalry found the Roman baggage, which had been sent on ahead of the army, and soon the entire Samnite cavalry force was attracted by the plunder. The Roman cavalry took advantage of the inevitable disorder that followed, and drove the Samnite cavalry off the battlefield. That left them free to ride around the main Samnite army and attack the infantry from the rear. Trapped between two Roman forces the Samnite line finally crumbled, and the army scattered. Livy states that the Samnites suffered very heavy losses, amongst them the commander of the army, who was killed by the Roman cavalry.
In the aftermath of this defeat the Samnites attempted to negotiate a peace deal. They found a scapegoat for the war in Brutulus Papius, an aristocrat who had been responsible for the renewal of the war after an earlier truce, but he killed himself before he could be handed over to the Romans. The Samnites had to make do with handing over his body, along with all Roman prisoners and booty captured during the war.
These peace offerings arrived at a Rome that was in a triumphant mood, and they were rejected. The war would continue in 321 BC, when the Romans would suffer one of the most embarrassing defeats in their history, at the Caudine Forks.