Agree with Parris.

Many more reasons for a war.

• Wars of conquest
• Wars of liberation
• Wars over materials, turf, land... (most common wars)
• Wars of vengance
• Wars to sustain economic power

Add you own lol... Luckily we dont live in the days where my king didnt like yours because of something my prince did to your princess so thousands of us end up dying, while said prince, princess and kings sit back and make friends again.