Although Morgenstern at first was completely absorbed by the writing of the Theory of Games with von Neumann, it soon became one activity amongst several. We have portrayed his return to game theory as partly an early reaction to upheaval and war; an attempt to construct a mathematics of social configuration. As reactions go, it was an abstract, intellectual one – the theoretical analysis of coalitions and compensations, with the “distant hope of some application to social phenomena”, as von Neumann described to Ulam. By 1941, however, the very events that had earlier fired von Neumann's imagination had culminated in American involvement in war, and he was drawn from the distant observation of political drama to actual participation in the conflict. He became directly, physically involved, interacting with military officers, incessantly moving about, boarding ships and submarines.

With that involvement came a significant, unforeseeable moment in the history of game theory: this new mathematics made its wartime entrance into the world, not as the abstract theory of social order central to the book, but as a problem-solving technique. In the course of World War II, a small, narrow part of the mathematics, far removed from the stable set in either content or philosophy, was adopted in the emerging field of operations research. What might be called the theory's social integration occurred in this context.