One disadvantage of the phalanx was that it was only effective when fighting in large, open spaces, which left the Romans at a disadvantage when fighting in the hilly terrain of central Italian peninsula. In the 4th century BC, the Romans abandoned the phalanx in favour of the more flexible <answer>manipular formation</answer>. This change is sometimes attributed to Marcus Furius Camillus and placed shortly after the Gallic invasion of 390 BC; it is more likely, however, that they were copied from Rome's Samnite enemies to the south, possibly as a result of Samnite victories during the Second Samnite War (326 to 304 BC).
What fighting formation would eventually replace the phalanx in battle?
manipular formation