A Single Misunderstood Radio Message Resulted in the U.S. Victory At The Battle of Cape Esperance

Clear communications is a vital aspect of victory for any military and history is replete with examples of communications screw-ups causing lost battles and disastrous casualties. At Battle of Cape Esperance during the Guadalcanal Campaign during World War II, a misunderstood radio message resulted in the U.S. Navy winning a significant victory against the Japanese Navy after its humiliating defeat at the Battle of Savo Island where the U.S. lost four heavy cruisers and more than a 1,000 sailors on the night of August 8-9, 1942.

With the U.S. invasion of the island of Guadalcanal in early August 1942, both the U.S. and Japanese Navies found themselves at relative parity to each other.  In June, the U.S. Navy had sunk four of Japan’s six fleet carriers losing the USS Yorktown in the exchange. This shift in the balance of naval power allowed the U.S. to go over to the offensive and make its landing on the island to prevent an airfield being built there interdicting U.S. supply lines to Australia.  The Japanese for their part were just as determined to hold it.

While the initial landings were a complete success, seeing the Japanese garrison driven off into the jungle, losses to fighter planes on the two U.S. carriers covering the landings cause their withdrawal out of range of Japanese planes flying from bases like Rabaul at the northwestern end of the Solomon islands chain.  The U.S. held the airfield, renamed Henderson Field, and were able to provide their own air cover, while the Japanese found Guadacanal was at the limits of the range of most of their aircraft except for twin-engine bombers. Their single-engine fighters and dive bombers could reach the island but could only loiter over the area for about 15 minutes before having to turn back. The result was that the Japanese could exert naval control of the waters around Guadalcanal at night, but would have to be at least 200 miles from the island by daybreak or risk attack by air from Henderson field.  The U.S. could land reinforcements during the day but would have to be well away from the island after dark when Japanese battleships, cruisers, and destroyers could sink their transports.

For both sides, this meant desperate attempts to resupply and build up their forces on the island, with whatever they could muster.  The Japanese were unable to use their slow-moving transports because they could not be clear of American air attacks by dawn so they employed destroyers and other fast warships in making supply runs. The U.S. could send transports into those waters but would need to screen them with warships and air cover from Henderson field in order for them to quickly unload and get clear themselves

On October 11, 1942, the Japanese attempted to make a high-speed run at night to deliver personnel, supplies, and equipment to their troops.  One of the logistical problems was that destroyers could not carry some of the heavy equipment like artillery and vehicles on their decks so they used a pair of fast seaplane carriers and their flight decks instead. The Japanese unappealingly called these runs “Rat Transportation,” the Americans had their own name for it, “The Tokyo Express’

Another Night, Another Run

The Japanese wanted to recapture Henderson Field, and were trying to build up their forces for a planned attack on October 20. In preparation, the Tokyo Express ran back and forth almost nightly landing troops from the Japanese 2nd and 38th Infantry Division on Guadalcanal, totaling around 17,500 troops. In addition, the seaplane carrier Nisshin was used to transport heavy equipment to the island, That was what they were up to and busy with from 14 September to 9 October. Cothoseast Watchers positioned on the islands approaching Guadalcanal were able to give location reports on these ships making their runs, but there was little the U.S. could do to stop them at night after the loss of 5 cruisers at the Savo Island battle only two months before. Our own carriers could not approach close to Guadalcanal to intercept them during daylight without running the risk of being overwhelmed by Japanese air attacks from Rabaul.

Japanese Vice Admiral Gunichi Mikawa’s Eighth Fleet staff scheduled a large and important run on 11 October. They were to transport 728 soldiers, four large howitzers, two field guns, one anti-aircraft gun, and a large assortment of ammunition and other equipment from the Japanese naval bases. All these were still part of their 20 October plan.

Meanwhile, Major General Millard Harmon of US Army Forces in the South Pacific had convinced Vice Admiral Robert Ghormley, who was the overall commander of Allied forces in the South Pacific, that they would need to reinforce the marines on Guadalcanal so that they could defend the island from the Japanese attack that they expected to occur. He agreed, and so on 8 October, 2,837 soldiers of the 164th Infantry Regiment from the US Army’s Americal Division departed on transports for Guadalcanal expecting to arrive on October 13th.

To protect the transports from Japanese surface ships at night and limited Japanese air attacks during the day, Ghormley dispatched his remaining 2 heavy cruisers and 2 light cruisers, and 5 destroyers. This task force would proceed ahead of the transport group and attack any Japanese warships that attempted to reach the transports. So in this battle, you had two fleets about to meet each other with the same mission, to ensure their respective reinforcement convoys would get through and land their troops and supplies

October 11 Chronicles

8:00

Under the command of Rear Admiral Takatsugu Jojima, the destroyers Asagumo, Natsugumo, Yamagumo, Shirayuki, Murakumo, and Akizuki departed their anchorage in the Shortland Islands at 1400 hrs and steamed down the Solomons Channel at high speed towards Guadalcanal, screening the seaplane carriers Nisshin and Chitose.

The Japanese 11th Air Fleet also conducted two airstrikes on Henderson field hoping to pockmark the runway and destroy Allied aircraft to protect the reinforcement group’s approach to Guadalcanal. These airstrikes were intercepted and failed, but they were able to prevent the air force bombers from finding and attacking their reinforcement group coming down “The Slot” as it was called.

Three Japanese heavy cruisers formed a separate bombardment group as well. These ships were tasked with bombarding Henderson field that night to further disrupt any attempt to launch a retaliatory air strike against the ships landing troops as they retired back up the slot in the early morning hours.

14:45

Jojima’s supply convoy was sighted by the Allied reconnaissance aircraft 210 miles between Kolombangara and Choiseul. It was reported as two cruisers and six destroyers.

16:07

Rear Admiral Scott was notified of Japanese warships approaching Guadalcanal with expected arrival in the late evening and he turned his ships to intercept them.

23:32

The Chitose and Nisshin were at the Northern tip of Guadalcanal disgorging their troops and equipment unaware that U.S. ships were stalking them in the dark. The radar on the USS Helena detected Japanese warship ships around 27,700 yards away. They tracked the Japanese force that was covering the supply convoy without knowing its actual mission.

Admiral Scott in maneuvering his squadron into a position to fire on the Japanese found his own flagship, the Cruiser San Francisco had misunderstood an order to turn as a column in trail and executed a simultaneous turn followed the light cruiser Boise which threw his three leading destroyers out of battle formation. While this was occurring Scott received the radar contact message from Helena about enemy ships 27,000 yards distant. Scott believed the Helena was tracking their three out of formation destroyers trying to get back to the front of the formation and took no action.  On the bridge of the Helena they watched what they were sure was a Japanese column of ships getting closer and closer.

23:45

When the contacts on his radar closed to the nearly point-blank range of fewer than three miles, an exasperated Capt. Gilbert C. Hoover on Helena radioed Scott on the San Francisco for permission to open fire as the Japanese ships, and he thought that Scott was aware of the approaching Japanese ships. By now, the radar on his own flagship had detected the Japanese, but he was not informed of the sighting.  Hoover’s message to Scott sought immediate clearance to fire on ships Scott was still thinking were his own destroyers using the standard message text, “Interrogatory Roger.”

Scott responded with “Roger” to acknowledge that the message was received but no to signal to Helena to open fire. Captain Hoover read the “Roger” response as permission for him to open fire and, USS Helen opened up with her fifteen six-inch guns, shortly followed by Boise, Salt Lake City, and to Scott’s surprise, the San Francisco which he was supposedly leading the fight from.

The three Japanese cruisers of the bombardment group detected Scott’s ships and reported it to Admiral Goto who thought they were actually seeing Admiral Jojima’s reenforcement group so they held their fire. Goto ordered his own ships to flash recognition signals to the ships to confirm their identity.  As his own flagship, the cruiser Aoba began flashing its signal lantern it was struck by the first of 40 shells fired by the American cruisers, mortally wounding Goto and killing dozens of men, the Aoba made smoke and staggered away holed and burning sure they were being fired at by their own side.

The confusion of the Japanese was also shared by Scott who believed his cruisers were firing on his own destroyers in error and at 23:47, he ordered his ships to ceasefire, which some of his ships, more sure of their target than their own Admiral was, refused to obey and continued firing.  It took several minutes for Admiral Scott to regain his situational awareness as he ordered one his missing destroyers to flash a recognition signal to be sure of her position to find that her close alongside his own flagship, and Scott gave the order to resume firing after five minutes.

In the wild melee of gunfire and torpedoes that ensued, Scotts Cruisers and Destroyers sank one of the Japanese heavy cruisers and two destroyers for the loss of one of his own destroyers the USS Duncan.  Admiral Jojima was able to land his reinforcements and escape unmolested detaching a couple of destroyers to assist the now mangled bombardment group as it limped away at reduced speed.  On Henderson field, Navy and Marine Corps pilots readied their planes to take off before dawn hoping to catch the Japanese withdrawing up the slot when the sun broke over the horizon.  The air attacks on the retiring Japanese ships began at 0700hrs on the morning of the 12th and were unrelenting until 4 pm that afternoon, sinking two more destroyers.\

Coming just months after the galling defeat at Savo Island, the Battle of Cape Esperance was a tactical victory due to a series of mistakes and foul-ups by both sides including the misunderstood radio communications between Admiral Scott and the skipper of the Helena.  Given that the battle was rightly considered a victory over the Japanese Navy in a night engagement which the Japanese excelled at, the tactical ineptness of Admiral Scott and his lack of situational awareness were overlooked by Nimitz.

A month later Admiral Scott would be killed along with Admiral Daniel Callahan during the Naval Battle of Guadalcanal. In that battle, Admiral Scott would fly his flag on the light Cruiser Atlanta while Callahan(who was senior) flew his on Scott’s old flagship, the San Francisco. In the midst of another confused, close-quarters battle in the dark, the San Francisco blasted the Atlanta with at least 19 eight-inch shells killing Admiral Scott on the Bridge.

He was awarded the Medal of Honor.