He tried to mathematically prove to himself that he would not run from a battle.
Previously he had never felt obliged to wrestle too seriously with this question.

In his life he had taken certain things for granted, never challenging his belief in ultimate success, and bothering little about means and roads.

But here he was confronted with a thing of moment.
It had suddenly appeared to him that perhaps in a battle he might run.
He was forced to admit that as far as war was concerned he knew nothing of himself.
A sufficient time before he would have allowed the problem to kick its heels at the outer portals of his mind, but now he felt compelled to give serious attention to it.
A little panic-fear grew in his mind.

As his imagination went forward to a fight, he saw hideous possibilities.

He contemplated the lurking menaces of the future, and failed in an effort to see himself standing stoutly in the midst of them.