 At 02: 15 on the night of 5 / 6 June, Commander John Murphy's Tambor, lying 90 nautical miles (170 km; 100 mi) west of Midway, made the second of the submarine force's two major contributions to the battle's outcome, although its impact was heavily blunted by Murphy himself. Sighting several ships, neither Murphy nor his executive officer, Ray Spruance, Jr., could identify them. Uncertain of whether they were friendly or not and unwilling to approach any closer to verify their heading or type, Murphy decided to send a vague report of "four large ships" to Admiral Robert English, Commander, Submarine Force, Pacific Fleet (COMSUBPAC). This report was passed on by English to Nimitz, who then sent it to Spruance. Spruance, a former submarine commander, was "understandably furious" at the vagueness of Murphy's report, as it provided him with little more than suspicion and no concrete information on which to make his preparations. Unaware of the exact location of Yamamoto's "Main Body" (a persistent problem since the time PBYs had first sighted the Japanese), Spruance was forced to assume the "four large ships" reported by Tambor represented the main invasion force and so he moved to block it, while staying 100 nautical miles (190 km; 120 mi) northeast of Midway.
