Marcus Minucius Rufus, left in command, managed to catch the Carthaginians off guard near their camp in Geronium and inflict severe losses on them in a large skirmish, while losing 5,000 Romans killed. This action caused the Romans, disgruntled with Fabius, to elevate Minucius to the equal rank of the dictator. Minucius took command of half the army and camped separately from Fabius near Geronium. Hannibal, informed of this development, laid an elaborate trap, which drew out Minucius and his army in detail, and then attacked it from all sides. The timely arrival of Fabius with the other half of the army enabled Minucius to escape, but with a substantial number of Romans killed. After the battle, Minucius turned over his army to Fabius and resumed the duties of Master of Horse.