For the operation, the 1st Marine Division was subordinate to Lieutenant General Walter Krueger's Sixth Army, MacArthur's major American ground command. Marine officers recoiled at Krueger's initial maneuver plan, which dispersed American forces, and won approval of their far superior plan for a concentrated landing by two regiments at one location. Further modification of the original plans resulted in the capture of Arawe (Operation Director), instead of Gasmata, on the south coast of New Britain. Arawe's seizure on 15 December 1943 by Brigadier General Julian W. Cunningham's 112th Cavalry Regiment (minus its horses) provided a radar site and a torpedo-boat base and obstructed the southern Japanese barge reinforcement route from Rabaul to Cape Gloucester.
The Marine plan called for the 7th and most of the 1st Marines to make the main landing on Yellow Beach 1 and 2 at Borgen Bay, about seven miles southeast of Cape Gloucester. While the 7th secured the beachhead, the 1st would advance along the coast and capture the airfields. The Marines would then extend their control over western New Britain. Meanwhile, seven miles southwest of Cape Gloucester, the 2nd Battalion, 1st Marines would hit Green Beach, near Tauali, and block the coastal trail, the airfield defenders' escape and reinforcement route. The 5th Marines initially remained in reserve on New Guinea.
By December 1943, Tokyo had declared outer defense areas like Rabaul, the Solomons, and eastern New Guinea expendable. The senior Imperial Japanese Army headquarters at Rabaul accepted the decision but believed the Allies must ultimately assault Rabaul. Hence Japanese officers aimed to preserve strength for an anticipated great battle there rather than dissipate men in actions elsewhere, like Cape Gloucester. By the date of Backhander, about 10,500 Japanese garrisoned western New Britain, around a third near Cape Gloucester, under command of Lieutenant General Yasuhi Sakai of the 17th Division.
The 1,500 men (including Robert Leckie) of Lieutenant Colonel James M. Masters' reinforced 2nd Battalion, 1st Marines hit Green Beach at 0748, 26 December and encountered no opposition. The command quickly established a 1,200-yard perimeter blocking the coastal track and prepared to hold it "against all comers." During the night of 29-30 December, two Japanese rifle companies smashed themselves futilely against the Marines' lines. On 11 January, Masters' battalion set out to rejoin the rest of the 1st Marines at the Cape Gloucester airfields.
The main landings on Yellow Beaches 1 and 2 started at 0746, 26 December. The Marines quickly encountered what they had been informed was a "damp flat" just off the beaches. As one Leatherneck snorted, it proved "damp up to your neck." The expansive swamp conferred one benefit on the Marines: The Japanese, knowing the actual nature of the ground, had ruled out the strip of coast as a potential landing area. While the Japanese provided little opposition on the ground, vengeful airmen attacked from Rabaul. Dive bombers sank the destroyer USS Brownson (DD-518) with 108 officers and men — far exceeding the 21 Marines killed and 23 wounded ashore on D-day.
That night the Japanese 2nd Battalion, 53rd Infantry staged a counterattack against the 2d Battalion, 7th Marines. The struggle — in the middle of a torrential rainstorm — characterized the atmospherics throughout the campaign. Excellent Marine fire discipline created lengthy periods of stillness. Only the transient flash of a muzzle blast or an infrequent slant of illumination from a flare momentarily lit the otherwise stygian darkness that obliterated all features of the combat arena. The firing of a single gun would provoke a response aimed by sound. The tempo of firing would swell to a chorus as other Marines and Japanese joined in and then would slowly die away only to ignite later at another part of the line. The losses sustained by the Japanese unit this night and the next two reduced it to a battalion in name only.
The 7th Marines' initial struggle had prompted Major General William H. Rupertus, the 1st Marine Division commander, to request his reserve regiment on the evening of D-day. Meanwhile, the 1st Marines, with excellent tank support, advanced northward. On the 28th, squads of Leathernecks following behind bunker-crushing M4 Sherman tanks overran the main Japanese defensive position in the regiment's path — Hell's Point. The next day, elements of the 5th Marines joined the 1st Marines for the final push, and by the end of the 30th, they held both airfields.
An admiring Army observer officer wrote of the advance:
The front line [Marine] was superb. These men were in splendid physical condition and spoiling for a fight. There were like hunters boring in relentlessly and apparently without fear. I never heard a wounded marine moan. The aid men, unarmed, were right up in the front lines getting the wounded.
General Rupertus delegated the task of extending the Marine holdings to the southeast to his assistant division commander, Brigadier General Lemuel C. Shepherd. On 2 January 1944, Shepherd commenced his advance with two battalions swinging like a door across the front of a third battalion. One officer described what this grand scheme looked like to the average Marine: "You'd step off from your line in the morning, take say ten paces, and turn around to guide on your buddy. And — nobody there, Jap or marine. Ah, I can tell you it was a very small war and a very lonely business."
The advancing 3d battalions of the 5th and 7th Marines ran into a stream soon dubbed Suicide Creek. There, expertly camouflaged Japanese waited in cavern-like positions formed by the arching roots of giant trees and within dense masses of bush. Just as invisible as the defenders were their cleverly interlocking fire lanes that turned the few yards of open ground in the stream bed into a deadly kill zone. By 5 January, when Shepherd's Marines cleared Suicide Creek and continued their advance, they had mauled two Japanese battalions but at the serious cost of 41 Marines killed or missing and 218 wounded.
Between 6 and 16 January, Shepherd continued his advance, successively capturing Hill 150 and well-defended, in places cliff-like Aogiri Ridge. Rupertus declared that the latter would henceforth be called "Walt's Ridge" after Lieutenant Colonel Lewis Walt, commander of 3d Battalion, 5th Marines. In thick undergrowth where visibility scarcely extended ten yards, Walt personally helped manhandle a 37-mm gun to the crest of the ridge where its fire broke Japanese resistance. When the Marines secured Hill 660 near the coast on 16 January, it marked the end of major fighting at Cape Gloucester. For the Japanese, however, it did not mark the end of major dying.
By 21 January, Japanese forces in western New Britain were under orders to withdraw to the east. The Marines pursued them vigorously with patrols ranging from six men to as many as a reinforced battalion. The breakdown of Japanese logistics and medical services shattered their normally fierce comradeship. Scarcely a mile of the region's interior trails was unmarked by rotting corpses and prone, pathetic abandoned soldiers, sick with dysentery or malaria or rotting with fungal infections. Some stoically waited to see their first American before blowing themselves up with a hand grenade. But the Marines captured an unusually large percentage of these men before the Leathernecks were relieved by Army troops in May and left New Britain to recuperate and retrain.
Marine casualties in western New Britain eventually numbered 310 killed and 1,083 wounded. At least 50 men were injured by falling trees, about half fatally. Japanese losses totaled some 3,868 killed and 420 captured — the latter about 4 percent of the region's garrison, one of the highest percentages of the war for a Pacific campaign.
Operation Backhander fell at a turning point in the Pacific war. Conceived when caution still governed planning, it was executed just as the disastrous effects of attrition on Japanese air and sea elements and the massive surge of American resources permitted U.S. forces to shift to a vastly quickened tempo of advance. Massive work by three engineer battalions barely made one of the Cape Gloucester airfields operable before its usefulness was negated by unanticipated lightning Allied advances into the Admiralty Islands and on New Guinea.
Four campaigns transformed the 1st Marine Division into an elite body of connoisseurs of human misery. Thus profound respect is due the veterans' opinion: Cape Gloucester was the most physically awful place they fought.