In the wake of agreeing to a two-week cease-fire on April 7, both the United States and Iran are claiming victory in their war. Each says the same thing: We held out and the other guy blinked first. In fact, both decided to call it a draw. And some sort of outcome like this was always likely, because the structure of the game constrained the decision-making of the players—even players as idiosyncratic as U.S. President Donald Trump and the leaders of the Islamic Republic. Wars have three phases: an opening, a middle game, and an endgame. As in chess, the opening involves deploying forces and engaging the enemy. If that doesn’t produce a quick victory, the contest moves into a middle game in which the two sides fight it out and try to get one another to surrender. As the trends in battle become clear, eventually the rough shape of a logical outcome emerges and the war enters its endgame, during which the details of the final settlement are hammered out.…