Bargaining scholars predict rapid power shifts cause preventive war. But cases with rapidly shifting power often remain peaceful. To explain the dogs that don’t bark, we introduce instant, repeated, costly militarization into Powell’s (1999) conventional-weapons power transition model. First, we rationalize preventive war during long, slow, complete-information power shifts. Second, we find that where past research into conventional shifts predicts war, a grand bargain backed by the decliner’s threat of war emerges as a second equilibrium. Because war and a grand bargain both prevent power from shifting, declining powers deploy them under the same conditions. Our grand bargain survives war-causing hazards, and some latent shifts. It occurs after incremental militarization causes repeated appeasement-like concessions, and when power shifts are instant, slow or fast, and perfectly observed; suggesting conventional shifts induce grand bargains under surprising conditions. The Great Game’s end fits our grand bargain, but that British elites seriously considered war.