'Lockjaw' was the Allied overall designation by General Douglas MacArthur’s South-West Pacific Area command for operations against Kavieng at the north-western tip of New Ireland off the north coast of New Guinea (1942/12 March 1944).

As the Japanese started to advance into New Guinea and nearby islands during the early months of 1942, the only Australian defence force available for New Ireland was part of the Australian 1^st Independent Company located at Kavieng. The Japanese launched a large air attack on Kavieng on 21 January 1942 and the Australian unit withdrew into the jungle. Two companies of the 2^nd Maizuru Special Naval Landing Force, totalling some 500 men, were transported from Guam island in the Mariana islands group and on 23 January occupied Kavieng. On 30 January the Australian unit tried to leave New Ireland aboard its station ship, but this was damaged by a Japanese air attack and escorted to Rabaul on New Britain island, where the troops and crew surrendered. The estimated 200 Europeans remaining on the island were interned.

The Japanese established the 14^th Base Force and elements of both the 5^th Kure Special Naval Landing Force and 5^th Sasebo Special Naval Landing Force at Kavieng, whose harbour was quickly developed as a secondary fleet base to support the main base at Rabaul. Detachments of the special naval landing forces played a more active role when they were committed to the unsuccessful 'Re' assault on Milne Bay at the eastern end of New Guinea in August 1942.

Elements of Vice Admiral Nishizo Tsukahara’s 11^th Air Fleet were stationed on New Ireland with airfields at Kavieng, Panapai just to the south-east, and Namatanai and Borpop on the lower part of the north-east coast. The naval commander at Kavieng was Rear Admiral Ryukichi Tamura.

In July 1942 the Allies took the decision to retake New Ireland, and scheduled this 'Lockjaw' invasion for April 1944 with the object of establishing a minor fleet base and six airfields from which the Allies could exert additional pressure on the Japanese main base area round Rabaul, and later to support operations into the Marshall and Caroline island groups. The Allies bombed Kavieng on an irregular basis, this being increased in frequency and intensity as the noose closed around Rabaul.

The Japanese strengthened Kavieng to help protect Rabaul between late 1943 and early 1944, and at the same time the pace and weight of Allied air attacks increased. The 230^th Regiment of Lieutenant General Sadaaki Kagesa’s 38^th Division was detached from Rabaul and arrived in October 1943, and was followed by the 1^st Independent Regiment from Japan between late 1943 and early 1944. Both units were controlled by Major General Takeo Ito, the commander of the 38^th Division's infantry group. These units were formed into the 40^th Independent Mixed Brigade at Namatanai in May 1944, and this came under the direct control of General Hitoshi Imamura’s 8^th Area Army at Rabaul. The total number of Japanese army and navy personnel on New Ireland was in the order of 10,000.

Scheduled for launch in April 1944, the 'Lockjaw' landings by Major General Allen H. Turnage’s 3^rd Marine Division and Major General Rapp Brush’s 40^th Division was cancelled on 12 March. The cancellation resulted from the appreciation that the assault would not be worth the casualties as both Rabaul and Kavieng had by this time been effectively neutralised by Allied air and naval power. The Allied-controlled islands that had been secured around Rabaul also served to isolate New Ireland and the Japanese forces there sat out the remainder of the war.

On 19 September 1945, Major General Kenneth W. Eather, commanding the Australian 11^th Division, accepted the surrender of the Japanese forces on New Ireland.