Which was the first war fought in the history of mankind?

If we define war as a large-scale violent conflict between two states employing the military, the earliest recorded wars might have taken place between various city states in the Mesopotamian region during the period 3,000-2,300 BC in the Bronze Age. The first recorded evidence of such a war was the one between the two city states Lagash and Umma, estimated to have taken place in 2525 BC. From the stone slabs bearing inscriptions related to the war, it could be inferred that the war employed professional soldiers wearing helmets who moved on chariots. The weapons employed were maces and swords.