Civilian control of the military is the constitutional principle that vests ultimate authority over the armed forces in elected officials rather than professional officers. McCullough presents this concept as the foundation for what he considers Harry S. Truman’s most unpopular, yet necessary, presidential decision: firing General Douglas MacArthur during the Korean War. As public and political criticism mounted, Truman held firm, believing he was upholding his oath of office. He later explained that “The Constitution stated clearly that there will be civilian control over the military” (84), making the decision a straightforward matter of duty. By acting on this principle despite the immense backlash, Truman demonstrated a core aspect of his character, prioritizing constitutional order over personal popularity and political expediency.

The Marshall Plan was the American program initiated after World War II to rebuild the economies of the Allies and save “Western Europe from economic and political ruin” (78). McCullough identifies it as a landmark achievement of the Truman administration and a testament to American ingenuity and generosity. He situates the plan within a broader context of national vitality, noting that America’s most significant accomplishments often arise from a creative energy that is separate from politics. The Marshall Plan thus serves as a prime example of the nation’s capacity for large-scale problem-solving and its role in shaping a stable postwar world.

The Northwest Ordinance of 1787 was a statute passed by the Continental Congress that established the framework for governing the territory that would become the states of Ohio, Indiana, Illinois, Michigan, and Wisconsin. McCullough identifies it as “one of the most far-reaching steps in the right direction in our whole history” (106), arguing that its provisions on governance, education, and civil liberties set a high standard for the nation’s westward expansion. The ordinance’s most significant clause forever prohibited slavery in these future states. 

The ordinance’s creation was heavily influenced by the lobbying of Manasseh Cutler, a Yale-educated pastor and polymath. Furthermore, Cutler insisted on provisions that set aside land for public universities, establishing a foundational link between national expansion and education. McCullough describes the legislation as a prime example of how principled lawmaking can proactively shape the values of a nation.