What are the reasons that made war start?

Causes of the Civil war- The north and south arias of the U.S.A  went  along different lines. The south remained a predominantly agrarian economy while the north became more and more industrialized. Different social cultures and political  developed. All this trouble  led to disagreements on issues such as taxes, tariffs and internal improvements as well as states rights versus federal rights and laws.

Causes of WWI- The European powers in the four decades heading  up to war. Additional causes were militarism, a complex web of alliances, imperialism, and nationalism. The great powers ( Italy, France, Germany, Britain, Austria-Hungary, and Russia )

http://en.wikipedia.org/wiki/World_War_I

Causes of WWII- The rise of Italian Fascism, Japanese Militarism. Invasion on  China. The trouble all began in Germany.

Do you want peace in the world? do you want war? are you sick of war?