The paper introduces a prototype decision support system for rapid exploratory wargaming of ground combat together with a conceptual framework for human-machine teaming. An AlphaZero agent provides continuous, GPS-device-like advice on how blue/red should proceed from the current situation to meet/prevent the long-term mission objective for blue. A controlled experiment with 100+ senior officers provides concrete evidence that the utility of wargaming in a digital environment improves with an AlphaZero agent in the team of players.