From Site: HyperWar: US Army in WWII: CARTWHEEL--The Reduction of Rabaul The Battle of the Bismarck Sea The Australian defense of Wau had a third consequence that was more far-reaching than even the most ebullient Bulolo Valley veteran (if anyone was ebullient after fighting in the mud, mountains, and heat) realized at the time. It helped lead to the destruction of an entire Japanese convoy and the subsequent weakening of Lae.16 Okabe's attacks against Wau had so depleted his meager force that the Japanese at Rabaul, who were determined to hold Lae and Salamaua at all costs, became worried. The 20th and 41st Divisions could not be spared from Wewak and Madang. Thus Imamura, Adachi, and the naval commanders decided to send the rest of the 51st Division in convoy to Lae. They planned very carefully. They were well aware of the havoc that airplanes could wreak on troop transports. Guadalcanal had demonstrated that point, and if final proof was needed, Adachi had had it in the destruction of part of Okabe's shipment in January. Had it been possible for the convoy to sail from Rabaul to Madang and land the troops there to march to Lae, the ships could have stayed out of effective range of Allied fighters and medium bombers; heavy bombers, thus far relatively ineffective against ships, were not greatly feared. But there was no overland or coastal route capable of getting large bodies of troops from Madang to Lae. It was therefore necessary to sail directly to Lae and thus come within range of fighters and medium bombers. The Japanese, employing almost two hundred planes based at Rabaul, Madang. Wewak, Cape Gloucester, Gasmata, and Kavieng, hoped to beat Allied planes down out of the air and to provide direct cover to the ships. But the Allies had deduced Japanese intentions. Ship movements around New Britain in late February, though not part of the effort to reinforce Lae, were noted by Allied reconnaissance planes. As a result air search was intensified and air striking forces were alerted. On 25 February General Kenney and his subordinates came to the conclusion that the Japanese would probably try to put more troops ashore at Lae or Madang.17 Not only were the Allies warned; they were also ready. By the end of February airfields in Papua, with those at Dobodura near Buna carrying the biggest load, based 207 bombers and 129 fighters. The Southwest Pacific had no aircraft carriers and few if any carrier-type planes that were specifically designed for attacks against ships. But Kenney and his subordinates had redesigned the nose of the B-25 medium bomber and installed forward-firing .50-caliber machine guns so that the bomber could strafe the deck of a ship and thus neutralize all her exposed antiaircraft guns. Further, they had practiced the skip-bombing technique that proved particularly effective in sinking --39-- JAPANESE TROOP TRANSPORT UNDER ATTACK by B-25's, Battle of the Bismarck Sea. ships.18 Once warned, the Allied airmen prepared detailed plans for striking the convoy and executed a full-scale rehearsal off Port Moresby. At Rabaul, 6,912 Japanese soldiers boarded eight ships. The ships weighed anchor about midnight of 28 February 1943 and, with eight destroyers as escort, sailed out of Rabaul and westward through the Bismarck Sea at seven knots. At first bad weather--winds, mist, and rain--hid them from the air, but soon the weather began to break and Allied patrol planes sighted the convoy first on 1 March and again the next morning off Cape Gloucester. As it was still beyond the reach of medium bombers, heavy bombers from Port Moresby attacked it in the Bismarck Sea. They sank one transport and damaged two others, a good score for heavy bombers. Survivors of the sunken ship, about 950 in number, were picked up by two of the destroyers which made a quick run to Lae to land the men after dark. The destroyers returned to the convoy on the morning of 3 March. During the night the convoy had sailed through Vitiaz Strait and into the Solomon Sea, tracked all the while by an Australian Catalina. But now the ships entered the Huon Gulf in clear daylight, and were within range of medium bombers. The Allied planes that had organized and rehearsed --40-- for the attack assembled over Cape Ward Hunt at 0930 and set forth for the kill. The Japanese had failed to destroy Allied air power in advance, and the convoy's air cover was ineffective. Starting about 1000 and continuing until nightfall, American and Australian airmen in P-38's, P-39's, P-40's, Beaufighters, A-20's, A-29's, Beaufort bombers, B-17's, B-24's and B-25's pounded the luckless Japanese from medium, low, and wavetop altitudes with resounding success. All remaining transports, along with four destroyers, sank on 3 and 4 March. After night fell motor torpedo boats from Buna and Tufi swept in to finish off crippled ships and shoot up survivors in the water. Of the 6,912 troops on board, 3,664 were lost. Including those taken by destroyer to Lae, 3,248 were rescued by the Japanese. The sinking of eight transports and four destroyers in "the most devastating air attack on ships" since Pearl Harbor was a tremendous victory, and it was won at a cost of thirteen killed, twelve wounded, and four Allied planes shot down.19 The Japanese quickly changed their plans for future shipments. They decided to send no more convoys to Lae. Large slow ships would be sent only to Hansa Bay and Wewak; high-speed ships and small craft would run to Finschhafen and Tuluvu on the north coast of New Britain. Small coastal craft would take men and supplies to Lae from Finschhafen and Cape Gloucester, and some men and supplies would be sent overland from Finschhafen to Lae. In emergencies supplies that were absolutely required at Lae would be sent in by high-speed ships or submarines. The main body of ground forces eventually intended for Lae would be sent overland after completion of a road, already under construction, from Wewak through Madang to Lae.
Am impressed with what the heavy bombers did. Having said that, '24 and '17 crews also trained in skip bombing so I'm wondering if they attacked this way or from altitude. Hard nose B-25s are just wonderful things. Menacing looking bits of gear. Almost reads like a free for all for the aircraft.
