The Japanese airstrike at Pearl Harbor in 1941 began the Pacific War. Their aircrafts had done enough to wipe out the battleships and most of the aircrafts stationed there, but U.S. aircraft carriers remained elusive. The U.S. Pacific Fleet could call upon four of them for further naval battles in the Pacific War, and they would play their part in numerous naval battles.
Among them was the Battle of Midway, in 1942, which was a great victory for the Allies. During this battle their three aircraft carriers wiped out a larger Japanese fleet which consisted of four aircraft carriers. Four IJN aircraft carriers, along with hundreds of their aircrafts, were lost in the battle. Midway Island was also held by the Allies.
After this victory, the Allies began a series of advances in the Southeast Pacific. The first of these advances began at Guadalcanal months after the Battle of Midway. Thousands of U.S. Marines landed on the shorelines of Guadalcanal, and quickly advanced towards Japanese airfields.
Henderson Field was the vital airfield that was soon captured by the advancing U.S. Marines. It was here that the Marines held out for months, in which time numerous battles around the airfield emerged. During these battles the Japanese troops were defeated and could not retake the airfield.
Their supply line relied upon the Imperial Japanese Navy transportation ships which shipped further reinforcements and supplies to the region. However, the Allies gradually curtailed this supply line in a series of naval battles around Guadalcanal, and with their aircrafts which bombed Japanese transport ships out of the water. Only a few thousand Japanese troops reached Guadalcanal, and they had little in the way of supplies for the campaign.
By early 1943 it was clear that the Allies were winning the campaign as they advanced further in Guadalcanal, and gradually Japanese troops withdrew. As such, the Japanese began to reinforce their positions in New Guinea where the Allies were also beginning to advance further. Japan required thousands of additional troop reinforcements to halt the Allied advance toward Lae.
To give them the reinforcements required in New Guinea the orders were given for a supply convoy to set sail from the military base of Rabaul in the northern Solomon Islands. A convoy of some eight transport ships with thousands of troops aboard, and other supplies, left Rabaul and headed towards New Guinea in the month of February 1943. Eight Japanese destroyers escorted them.
However, the Allies intercepted the ships in the Bismarck Sea as they moved within range of their aircrafts. It was here that the Allies wiped out the Japanese convoy's transport ships with their bombers. As such, the expected Japanese reinforcements did not arrive in New Guinea, and the Allies maintained their advance toward Lae.