World War III was a global conflict that started in 1962 and ended in 1975. It involved most of the world's nations- including the United States and USSR- and eventually became a conflict between two opposite pacts- NATO and the Warsaw Pact. It was the most widespread war in history, with more than 230 million military personnel mobilised. In a state of "total war", the major participants placed their entire economic, industrial, and scientific capabilities at the service of the war effort, erasing the distinction between civilian and military resources. Marked by significant events involving the mass death of civilians, it is the deadliest conflict in human history, resulting in over 210 million fatalities.