Alfred von Schlieffen his troops were pushed back in the Battle of the Marne. Schlieffen was perhaps the best-known contemporary strategist of his time, although criticised for his "narrow-minded military scholasticism." Schlieffen's operational theories were to have a profound impact on the development of manoeuvre warfare in the 20th century, largely through his seminal treatise, "Cannae", which concerned the decidedly un-modern battle of 216 BC in which Hannibal defeated the Romans. Cannae had two main purposes. First, it was to clarify, in writing, Schlieffen's concepts of manoeuvre, particularly the manoeuvre of encirclement, along with other fundamentals of warfare. Second, it was to be
Early Middle Ages had broken down, and the Roman army comprised mainly barbarians and soldiers recruited for a single campaign. The general decline in discipline also led to the use of smaller shields and lighter weaponry. Not wanting to share the glory, Eastern Emperor Valens ordered an attack on the Therving infantry under Fritigern without waiting for Western Emperor Gratian, who was on the way with reinforcements. While the Romans were fully engaged, the Greuthung cavalry arrived. Only one-third of the Roman army managed to escape. This represented the most shattering defeat that the Romans had suffered since the Battle of Cannae (216