The first simulated atomic attack in Exercise Sunrise failed to locate the Home Fleet despite coming within thirty miles. A second attack reached the fleet on 12 December. The defence placed the battleship and three carriers in a box about ten nautical miles square, intended to keep one bomb from destroying or seriously damaging more than one high-value ship while retaining anti-submarine protection. The commander-in-chief later suggested that closer spacing could have improved submarine defence without increasing the atomic risk. The simulated bomb fell 4,500 yards from Dido and 6,700 yards from Vengeance, the nearest high-value target. Analysis based on the Bikini tests judged that particular attack ineffective.
Notable Point · 1:26:34-1:27:30
Atomic-bomb dispersal competes with anti-submarine protection
Exercise Sunrise tested how widely major ships could disperse against atomic attack while preserving an effective submarine screen.