Battle of Samnium

For some reason he had the camp built at a from tactical point of view bad place. When the Samnites arrived they built their camp near the Roman one; likely on a better spot. The distance will have been 300-500 meters. Obviously within hearing distance, but leaving room to maneuver.
That night the dictator tried to leave in silence in order to find a more favorable spot. But to have 10.000 men doing something in silence is almost impossible and the Samnite cavalry came to have a look.

The Samnite cavalry followed the Romans but could not attack in the dark. Cornelius kept moving until daylight. He did an attempt to rebuilt a camp, but the Samnite army was too close. He ordered battle formation. According to Livius he ordered to remove the luggage from the column first. That is probably true for the army followers, carts donkeys etc., but for the legionnaires it is more likely he presumed the battle line first, had his men drop off their baggage and then moved toward the enemy. Collecting the stuff and piling it up somewhere would have cost time, he didn't have and a mess when after the battle when the boys came to recollect their things.

We can safely assume the Roman battle formation was divided in manipels and the Romans used oblong shields.. like the Samnites did. In Liv.(8.8) Livius gives a large explanation about the reorganization of the army, be it before the Romans encountered the Samnites. See also Roman warfare. From the 5th till the 8th hour the battle was equal and the front line didn't really move. Assuming it was may or early June the fifth hour equals about 9 am the eighth about 4 PM (16.00h) and not 2 PM (14.00) as our translator states.
Look here for an explication of Roman time calculation .

So they had been fighting for 7 hours. Then a troop of Samnite cavalry discovered the Roman baggage. Why and how were they there, behind Roman lines? If they were a reconnaissance party they can have counted let say 8 to 10 men at the most. There would then have been more than enough donkey drivers etc. to fight those off. The main body of the cavalry was needed to cover the flanks. Since the battle was still indecisive, if there was a troop of cavalry in reserve the commander would have kept it there in order to prevent what was going to happen. Probably one or more men discovered the unprotected luggage, made a rush for it and many of his comrades followed. Now one of the flanks of the Samnites became unprotected. The opposing Roman cavalry must have seen this happen and asked the dictator what to do. He ordered them to wait until the Samnite riders had dispersed themselves over the booty and attack them then.
After having disposed of that part of the Samnite cavalry the way to the back of the Samnite army laid open. M. Fabius, master of the horse, led his troop there and attacked the Samnites from behind and brought the Romans the victory.