In January 1942, Japanese troops overpowered an Australian garrison at Rabaul, on the southwestern Pacific island of New Britain (now part of Papua New Guinea). By the summer of 1943, Rabaul served as a major Japanese base, with more than 100,000 troops garrisoned there.

At the end of April 1943, the Allies developed a plan to encircle Rabaul, codenamed “Operation Cartwheel.”  It called for General MacArthur to approach Rabaul from the southwest, through New Guinea and the southern Bismarcks, while Admiral Halsey advanced through the Solomons, forming pincers that would close in on the Japanese base.

On learning of the potential loss of a critical installation, the Japanese fleet assembled at Truk Atoll bent on relieving their endangered forces.

On 2 November 43, the 5th Bombardment Group (Heavy) and other air and naval units began the reduction of Rabaul with such great strength that the Japanese fleet was forced to withdraw rather than suffer the loss of their limited capital ships and their escorts.

On 11 November 43 (then Armistice Day), the 5th Bombardment Group (Heavy),  including Leo Carter’s 23rd Bombardment Squadron (Heavy), attacked Rabaul shipping.

On 28 February 43, the 5th Bombardment Group (Heavy),  again including Leo Carter’s 23rd Bombardment Squadron (Heavy), attacked Rabaul City.  It was Leo Carter’s 32nd of 48 missions.