In January 1943 Eighth Area Army ordered reinforcements to Lae, New Guinea.

Forewarned of the impending convoy by decrypted Japanese naval messages, MacArthur’s air chief, Lt. Gen. George C. Kenney, commander of Allied Air Forces and U.S. Fifth Air Force, sent repeated air attacks against the enemy ships. Allied pilots sank two troop transports, damaged another, and killed 600 Japanese soldiers. Only one-third of the intended Japanese reinforcements reached Lae, and these survivors salvaged only half of their equipment. Without reinforcements, the desperate attack on Wau failed. The defeated Japanese remnants fell back into the jungle, slowly giving ground toward Lae.

Repulsed at Wau and pressed by the Australians, Japanese forces on New Guinea urgently needed reinforcements. On February 19, 1943, U.S. Navy cryptanalysts handed MacArthur solid intelligence that the enemy was planning another major transport to Lae in early March. Kenney threw every available aircraft into a three-day struggle from 2 to 5 March, known as the Battle of the Bismarck Sea. Eight transports and four destroyers were lost in all. Of the 51st Division’s 6,912 troops, about 3,900 survived, but only 1,000 soaked, oil-stained, and dispirited officers and men reached Lae. Kenney’s destruction of the 51st Division condemned the Japanese to the strategic defensive on New Guinea.