Identify the characteristic of the nature of war that most requires flexibility of thought. Because of this characteristic, success on the battlefield depends in large part on the ability to adapt-to proactively change events to our advantage as well as to react quickly to constantly changing conditions.

The characteristic of the nature of war that requires flexibility of thought is known as fluidity

Explanation:

Fluidity as a concept of the nature of war can be described as the ability to adapt to the constantly changing sets of events. One has to condition the mind to give room for and possibilities for all the possible events, putting in mind the past events and accepting and analyzing whatever turn the events take.

Another very unstable aspect is the intensity of the war. It changes with time, being more intense at a moment and less intense at another. War will usually not maintain a constant rhythm of intensity, bringing in the idea of fluidity. One should be able to quickly adapt to these changes in intensity to be adequately prepared for the task at hand. While having more energy (or adrenaline rush) than is required for a mission isn't such a bad thing, the otherwise of this could be disastrous and even fatal.

The idea behind fluidity in war is simply to be always ready mentally, regardless of the twists and turns of the events. Quick adaptation to the development of events is very key. The battlefield is the last place to be caught slipping.