The first war ever recorded happened in 2700 B.C. , but there was a lot more unrecorded wars that happened before that happened.
First Sacred War happened in -595.
First Barbary War happened in 1801.
First Schleswig War happened in 1850.
First Carlist War happened in 1833.
First Peloponnesian War happened in -460.
First Taranaki War happened in 1861.
First Celtiberian War happened in -181.
First Rohilla War happened in 1773.
First Mithridatic War happened in -89.
First Messenian War happened in -743.
First Barons' War happened in 1215.
First Dacian War happened in 101.
First Servile War happened in -135.
First Macedonian War happened in -214.
First Matabele War happened in 1893.
First Margrave War happened in 1449.
First War of Kappel happened in 1529.