Chapter 8 analyzes the thinking of Harry Summers, especially his critique of the Vietnam War. Summers was an outspoken military practioner who exposed the harmful effects of applying academic (and untested) strategic theories in Vietnam. He believed most armed conflicts would be fought below the nuclear threshold and hence he maintained the principles of war, which he regarded as timeless, were still sound guides for crafting military strategy. This chapter discusses his model of war’s nature, which retreated somewhat from that of Eccles and Wylie because it paid less attention to war’s sociocultural dimension. It did, however, bridge to the modern model by reemphasizing the importance of the concept of Clausewitzian friction.