Arrow of Sagittarius - S1.E12

A landing party from the Mirai on Guadalcanal has close calls with both the Japanese on the island and with the attacking American forces. The Mirai witnesses the Battle of Savo Island, where the Allied naval force covering the landing is destroyed by the Japanese Eighth Fleet under Admiral Gunichi Mikawa. When the Japanese fleet withdraws without attacking American transports, the crew of Mirai think history as they know it — in which the fear of a possible air attack from US carrier forces caused the Japanese fleet to withdraw prematurely — remains unchanged, but Admiral Mikawa remarks to his staff that he is in fact aware that U.S. carriers are far away and cannot intervene. The withdrawal, in fact, is a part of a larger strategy. General Vandegrift receives a message from the Mirai warning that, at 3 am, an "arrow of Sagittarius" will strike his camp as a demonstration of their power and that his men should withdraw immediately if they value their lives.