The Second Northern War was caused because Norway and Sweden were fighting over land.
This war was caused because of a conflict between Spain, Germany, France, and the Dutch Republic.
This war was caused because of a conflict between Brazil and Sao Paulo (Paulistas or Emboabas)
The War of the Austrian Succession was caused because Spain, France and Germany wanted to take over Austria. (At the time that was their nemesis)
The war was caused because the poor people were treated less equally than the rich people so they fought for a raise in attention.
The Civil War Was caused because people in some slave states demanded to make slave free states.