The Romans were commanded by consulsDecius Mus and Fabius Maximus Rullianus, and amounted to about 38,000 men — 4 legions, a strong contingent of Roman cavalry, 1,000 chosen cavalry men from Campania, 4 allied and Latin legions and a strong contingent of allied and Latin cavalry. Their opponents were Samnites and Gauls, since the Etruscans and the Umbrians had returned to their territories to defend them from another small Roman army.
The two armies, of the same strength, arrived at the Plain of Sentinum but waited for two days to battle each other. Finally, unable to control the eagerness of their troops, the Romans attacked. Fabius faced the Samnites; Decius was opposite the Gauls. The Roman line initially buckled under the Gauls' chariots. Decius charged into the Gauls anyway. Although he was slain, Decius' charge inspired his men and they restored the Roman line. Fabius routed the Samnites and then flanked the Gauls to win the battle.