It was gratifying to read one of my favorite prejudices confirmed in McPherson's For Cause and Comrades about the private letters and diaries of the soldiers of the Civil War. Volunteers from the same towns often joined the same regiments, stayed together, and were able to write home about each other. North and South, soldiers noted that the men who were always fighting back home often turned out to be cowards and poor soldiers.
In my limited experience, it makes sense. The fighters are often those who are most concerned with their personal comforts and rights. Physical courage is what is needed at the point of action, but it usually requires moral courage to undergird it, or it is ephemeral - a thing of anger and the moment.