H.W 1 Why Does Genocide and War happen?

In my understanding of war and genocide, war is usually about political dispute, national crisis or fear and hatred. An example of Political dispute would be The Cold War, America against USSR and Communist Countries such as North Korea and North Vietnam. National Crisis such as the Great Depression lead the Japanese Imperials to strike across all of Asia to gain economic growth.  War could also lead to genocide because of fear and hatred. Genocide is the denial of one Minor's existence done by a Major organization or group. One example would be Pol Pot's genocide of Cambodians. This is my understanding of war and genocide.