Good article article on the role wargaming played in the Royal Navy's anti-Uboat campaign.
After Hitler lost the Battle of Britain, the Atlantic Campaign was his only real hope to force Great Britain out of the war.
Wargaming the Atlantic War (.pdf)
The Royal Navy did a remarkable job exploiting wargaming in this case. The combined games and after action reports from combat to solve problems and improved doctrine and tactics while the campaign was raging.
The only thing that ever really frightened me during the war was the U-boat peril.... Our lifeline, even across the broad oceans and especially in the entrances to the island was endangered. I was even more anxious about this battle than I had been about the glorious air fight called the Battle of Britain....
So we poised and pondered together on this problem. It did not take the form of flaring battles and glittering achievements. It manifested itself through statistics, diagrams, and curves unknown to the nation, incomprehensible to the public.
Winston Churchill,Their Finest Hour
I also had no idea that the Women's Reserve Naval Service played such a critical role.