George C. Marshall, famed U.S. World War II general and eventual U.S. Secretary of State and Nobel Peace Prize winner, on his first assignment fresh out of military school, told a fellow officer: Once an army is involved in war, there is a beast in every fighting man which begins tugging at its chains. And a good officer must learn early on how to keep the beast under control, both in his men and himself. Even for nations possessing a reputation for stringent compliance with the law of war, the annals of history, to include more contemporary military engagements, are littered with cases of atrocities committed by soldiers. All too often the beast wins, and because every nation has an obligation to minimize the reality described above, nations must continue to dedicate time, thought and resources to best prepare their forces for future military operations. Unrestrained warfare has a direct negative military impact on both winning the war and winning the peace. This corollary remains as true today as it has ever been. What is meant by a ‘reluctant warrior’? Put simply, a reluctant warrior is one who while ready to employ lethal force when the situation demands, is not eager to do so in “the moment”. He answers the questions: “Can I, If I, Should I”, and then takes decisive action – or employs uncommon restraint – with a goal of accomplishing the mission all the while staying true to the value imbedded in the U.S. Marines’ Hymn, “to keep our honor clean”. To fully develop the ‘reluctant warrior’ needed on today’s and tomorrow’s battlefields, this article will look at the role of legal regulation and the practice of military education and training, as well as some of the other factors that influence behavior and decisionmaking during instances of armed conflict. This article will also comment on the costs to the individual soldier and to the mission when a nation fails to prepare ‘reluctant warriors’.