quality:corruption, structural:summarization
Hoplite armies

During this period, Roman soldiers seem to have been modelled after those of the Etruscans to the north, who themselves are believed to have copied their style of warfare from the Greeks. Traditionally, the introduction of the phalanx formation into the Roman army is ascribed to the city's penultimate king, Servius Tullius (ruled 578–534). The phalanx was effective in large, open spaces, but not on the hilly terrain of the central Italian peninsula. In the 4th century, the Romans replaced it with the more flexible manipular formation. This change is sometimes attributed to Marcus Furius Camillus and placed shortly after the Gallic invasion of 390; more likely, it was copied from Rome's Samnite enemies to the south.