The Mahabharata details a War of Destiny.
The Iliad chronicles a King's imperialism masked by infidelity.
The Tain is the tale of a Cattle-Raid of Epic Proportions.
Each war can arguably be marked by what is important to each culture. The Pandavas and Kauravas are the sons of Gods and Demons, it is perhaps their Dharma to do battle.
Agamemnon's conquest mirrors the Mycenaean's expansion over the Minoan and, possible, ancient Turk culture.
The Ancient Hibernians were an agrarian people, mostly comprised of tribes, where livestock and farmland were shows of great wealth.
The question I pose is this: What defines a just war for a culture?
In the 1940's the Nazi Party felt justified in their war in Europe, feeling it was their destiny as a race to rule the Western world -- while this may seem monstrous to us, it was not only accepted but celebrated.
Conversely, the English and Americans would never declare war under a banner such as racial superiority, and as such, used their enemy's cause as a means of rallying others to their cause. They must be stopped.
At that same time, Adolf Hitler called the British war-mongers for their Imperialism in India, which they viewed as complete tyranny.
How would Agamemnon feel about Medb's war? Would Krishna view Cuchulainn was a worthy-enough warrior to drive his chariot?