This global conflict split the majority of the world's nations into two opposing military alliances. On one side was the Allies. On the other was the Axis powers. It involved the mobilization of over 100 million military personnel. This made it the most widespread war in history. It placed the participants in a state of "total war". The distinction between civil and military resources were eliminated. This resulted in the complete activation of a nation's economic, industrial, and scientific capabilities for the purposes of the war effort. Over 60 million people, the majority of them civilians, were killed, making it the deadliest conflict in human history. The financial cost of the war is estimated at about a trillion 1944 U.S. dollars worldwide, making it the most costly war in capital as well as lives.