A floor plot recreates uncertainty at sea

The floor game represented escorts and convoys in white and submarines in green, while officers observed through a small peephole rather than seeing the whole plot. That restriction was deliberate: an escort commander at sea did not possess a god's-eye view of the fight. Officers could play before and after instruction, making the exercise both a teaching device and a test of whether a method actually improved their decisions. Many of the Wrens running the games were only eighteen or nineteen, yet they had to synthesize intelligence, challenge visiting officers in play, and refine procedures under wartime pressure. The same games therefore trained commanders while helping WATU improve its systems against incoming operational intelligence.