War is a function of the migration of tribes. It is the expansion of one nation's cultural footprint. But this happens at a cost that includes genocide, rape, famine, and the spread of disease. It's not all glory to those participating. In ancient times (in western civilization) the most important wars were Rome's conquest of Gaul, Rome's wars against Carthage, the Macedonian conquest of the Persian Satrapies, the Greek wars between Athens and Sparta, and the Assyrian-Babylonian wars.
Old Empresario, I have a list as well. 1.The Greek-Persian Wars, 2.Alexander the Great Conquest, 3.Punic Wars, 4. Peleponesian War and 5.Visigoth Wars on Rome. Runners Up: The Trojan War, Babylonia Expansion Wars, Assyrian Wars and Corinthian War.