Battle of the Eastern Solomons. US and Japanese Admirals both suspect the other’s aircraft carriers are in the seas around Guadalcanal but don’t know where. At dawn they send out scout planes. In addition, Japanese light carrier Ryūjō, cruiser Tone and destroyers Amatsukaze and Tokitsukaze are sent into the fray to launch an aircraft attack on Henderson Field to smoke out the US carriers. However, they are spotted by a US Catalina flying boat from the Santa Cruz Islands at 9.35 AM and attacked by 29 dive bombers and 5 torpedo bombers from USS Saratoga at 4 PM. Ryūjō is badly damaged by 4 bomb hits and a torpedo (120 killed, 800 taken off by destroyers Amatsukaze and Tokitsukaze) and sinks at 8 PM. At 4.30 PM, 27 Japanese Aichi "Val" dive bombers and 15 Zero fighters from carriers Shōkaku and Zuikaku attack the US carriers USS Enterprise and USS Saratoga, which launch P-40 Wildcat fighters to fend off the attack. USS Enterprise is set on fire by 3 bomb hits on the flight deck (70 killed, 70 wounded), but the fires are contained and USS Enterprise is able to proceed at 24 knots under her own steam (returning to Pearl Harbour to be patched up again). Significantly, Japanese lose 33 fighters, 32 bombers and 7 float planes plus 61 valuable experienced airmen.
Invasion of Milne Bay (Eastern end of Papua). Japanese intelligence believes the Australian presence at Milne Bay, where Allies are building an airbase for their bombers, is 3 companies; in fact, the Australians have the veteran 18th Infantry Brigade as well as the inexperienced 7th Infantry Brigade totaling 8800 troops. At 7 AM, 809 SNLF troops leave Rabaul aboard the transports Nankai Maru and Kinai Maru (escorted by cruisers Tenryū and Tatsuta, 3 destroyers and 2 submarine chasers). Another 450 Japanese troops leave Buna in 7 barges, moving unescorted along the North coast of Papua to land in Goodenough Bay (they plan to cross the hills of the Stirling Ranges to attack Milne Bay from the rear). The barges stop on Goodenough Island (15 miles from shore) to hide during the day but they are spotted and destroyed by 12 RAAF P-40 Kittyhawk fighters, stranding the troops until October.
US submarine USS Guardfish sinks Japanese passenger-cargo ship Seikai Maru off Sendai harbor, Japan.
At 11.13 AM 100 miles East of Barbados, U-162 sinks Dutch SS Moena (4 killed, 83 survivors in 4 lifeboats picked up next day by British MV Cromarty and landed in Trinidad).
In the Kara Sea 55 miles West of Dikson Island, U-601 sinks Soviet SS Kujbyshev with a torpedo at 2.09 PM and tug Medvezhonok with 20 rounds from the deck gun at 2.42 PM. There are no survivors. In the Gulf of Finland, Soviet torpedo boat Burya and minesweeper T-204 sink while clearing German mines.
Overnight, 226 RAF bombers (104 Wellingtons, 61 Lancasters, 53 Stirlings, 8 Halifaxes) attack Frankfurt, Germany but the Pathfinder aircraft again get lost in cloudy weather and most bombs fall on the villages of Schwalbach and Eschborn. 6 Lancasters, 5 Wellingtons, 4 Stirlings & 1 Halifax are lost.