“Scenario planning” has become boardroom shorthand for preparation to deal with the unknowable. It’s a practice that is never more vital than in wartime, when a sea mine, cyberattack, or sanction can reroute supply chains overnight and send energy prices soaring.

Instead of betting on one forecast about how events will unfold, the most resilient CEOs are now rehearsing several plausible futures at once and deciding—before the missiles start dropping, the virus becomes a pandemic, or the markets seize up—what they will do in each.

It’s an approach that was pioneered by Shell precursor Royal Dutch Shell. In the 1970s the energy company began developing a set of vivid alternative futures involving potential oil-supply disruptions. Shell did not invent the idea of developing such scenarios, which had earlier roots in military and Cold War strategy, but it was the first major company to embed systematic scenario planning at the center of corporate decision-making, largely through the work of economist and planner Pierre Wack. His London-based scenarios team had Shell’s top managers rehearse what they would do if various crises arose.

The doomsday prep paid off. In the early 1970s, Shell’s leaders wondered what would happen if events in Saudi Arabia raised the price of oil. By the time the Arab oil embargo shook the world soon thereafter, sending prices rocketing, Shell knew what to do. It had already slowed refinery expansion and adapted its refineries to handle many types of crude—while competitors vacillated. The common view in the industry is that Shell came through the oil shock far better than any other major producer. The success of those exercises turned Shell into a case study for scenario planning, and the company still regularly publishes its “Shell Scenarios.”