Both the Peloponnesian War and the American Civil War have been dubbed “modern conflicts” due to their significant departure from the traditional methods of warfare that had previously existed. To understand these differences, one must look at the differences closely. The modern nature of the Peloponnesian War was based on strategy and tactics. Namely, the Spartans employed guerilla warfare strategies that did not exist previously. This caught the Athenians completely off-guard. Additionally, Sparta heavily employed naval warfare in combination with infantry troops.
This multifaceted approach laid the foundation for the strategies of warfare in WWI. The Civil War ushered in modern conflicts through its development of new combat systems. The Gatling Gun, The Ironclads, and primitive submarines were all part of Civil War combat. Even the traditional weaponry of the infantry changed things significantly. A bizarre as it may be, prior to the Civil War, battles would draw spectators to view the resultant carnage of the war. With the Civil War, there were attempts by “audiences” to watch the carnage.
However, they soon discovered that the battle of the Civil War did not treat spectators kindly. Namely, cannon fire and advices breach loading rifles led to spectators being injured or killed in the crossfire. This would alter the perception of war since the employment of more efficient weaponry would move the Civil War into a realm of warfare that is much closer to modern conflicts. While both of these wars did take place many years ago, they still influence the tactics and strategies of warfare today. As such, it might not be accurate to refer to them as modern wars as much as timeless wars.