BLUF:

Clausewitz states that war is inevitable; however the way in which war is waged is constantly changing. There are three enduring truths to war:

1. War is an instrument of policy -- winning a war means achieving political objectives.

2. War is a chaotic human endeavor -- war is dominated by three factors: Fog, Friction and Chance.

3. War is a clash of opposing wills 

War may be fought in a traditional (force on force) or irregular (fight by nonstate actors for legitimacy) manner. 

US adversaries are preparing to "win without fighting" in the next war. As a result, the competition continuum was created.