In 1942, Britain was losing the battle of the Atlantic, which meant it was losing the war.
This has a way of concentrating the mind, so it was prepared to try anything.
One of the desperate moves was to try war-gaming.
All that could be spared were a retired naval officer and eight young Wrens, for a group called Western Approaches Tactical Unit.
The young Wrens knew nothing of anti-submarine warfare of course.
This meant they had lots of questions.
As with any problem, questions are always the best place to start.
Q: Whereabouts in the convoy are the ships being attacked?
A: Usually in the centre, at night.
Q: How big is the convoy?
A: About eight miles square.
Q: What is the torpedoes’ range?
A: About two miles.
Conclusion: The U boats must be attacking from inside the convoy. Torpedoes can’t reach the centre from outside.
Q: What is the convoy’s speed?
A: Around 10 knots.
Q: What is a U boat’s speed?
A: Sixteen knots on the surface, six knots submerged.
Conclusion: The U boats are attacking on the surface, they are too slow when submerged.
Q: How long does it take to reload the torpedoes?
A: About half an hour.
Q: Would they do this on the surface?
A: No, they would submerge.
Conclusion: After an attack, a U boat will submerge and be left behind by the convoy.
They will then have to surface to catch up.
In having to answer the Wrens’ questions, the naval officer had to think like a U-boat commander, and that was the first time anyone had done that.
Instead of rushing around after the first ship exploded, they realised the destroyers had some time while the U boat reloaded.
They could let the convoy pass on and, after it was gone, search for the U boats that were reloading.
Because they were submerged, they were slower, and the destroyers could use Asdic (underwater radar) to locate them.
But first they had to prove it to the Admiral in charge, so they used a war game.
Admiral Sir Max Horton was an ex-submariner.
He took the role of a U-boat captain.
Five times he attacked the convoy, five times he was sunk by his unseen opponent, using these new tactics.
He asked to be introduced to his opponent, whom he hadn’t even seen yet.
His opponent was 18-year-old Wren Janet Okell, who’d been helping to devise the new tactics.
The Admiral was convinced, and the tactics began sinking U boats for real in the Atlantic.
WATU was expanded to eight male officers and 36 Wren officers and ratings.
During the war, they trained 5,000 naval officers in anti-submarine warfare.
At the end of the battle of the Atlantic, 75% of all U boats had been destroyed.
They discovered the value of asking new questions is you come up with new answers.
Which wouldn’t have happened without having to train those Wrens.
Asking questions that hadn’t been asked before wasn’t silly, in fact it won the battle of the Atlantic.
Dave Trott is the author of Creative Mischief, Predatory Thinking and One Plus One Equals Three