Intelligence and Allied command in the Ashigara operation

Decrypted information revealed Japanese movements, and the U.S. commander of submarines in the Southwest Pacific helped coordinate the Allied response. The claim that he personally directed every manoeuvre by Trenchant and Stygian is difficult to reconcile with the command structure and communications limits. Repeated tactical broadcasts would risk exposing the submarines' positions, while British and American submarine radio equipment could not communicate smoothly. Information therefore had to pass through multiple command centres. The theatre commander also had dozens of submarines and several Allied commands to coordinate, while the captains at sea were expected to handle their own boats. Shared intelligence and operating plans allowed that coordination without continuous instructions for individual manoeuvres.