As a kind of final security measure, IMAC was concerned about a last ridge of hills, some 2,000 yards to the front, and really still dominating too much of the perimeter. Accordingly, on 28 November, General Geiger ordered an advance to reach Inland Defense Line Fox. As a preliminary, to protect this general advance from a surprise Japanese attack on the far right flank, a raid was planned to detect any enemy troop movements, destroy their supplies, and disrupt their communications at a place called Koiari, 10 miles down the coast from Cape Torokina. The 1st Parachute Battalion, just in from Vella Levella under Major Richard Fagan, drew the assignment, with a company of the 3d Raider Battalion attached. While it had never made a jump in combat, the parachute battalion had been seasoned in the Guadalcanal campaign.
Carried by a U.S. Navy landing craft, the men in the raid were put ashore at 0400, 29 November, almost in the middle of a Japanese supply dump. Total surprise all around! The Marines hastily dug in, while the enemy responded quickly with a “furious hail” of mortar fire, meanwhile lashing the beachhead with machine gun and rifle fire. Then came the Japanese attacks, and Marine casualties mounted “alarmingly.” They would have been worse except for a protective curtain of fire from the 155mm guns of the 3d Defense Battalion back at Cape Torokina. With an estimated 1,200 enemy pressing in on the Marines, it was painfully clear that the raiding group faced disaster. Two attempts to extricate them by their landing craft were halted by heavy Japanese artillery fire. Now the Marines had their backs to the sea and were almost out of ammunition. Then, about 1800, three U.S. destroyers raced in close to the beach, firing all guns. They had come in response to a frantic radio signal from IMAC, where the group’s perilous situation was well understood. Now a wall of shell fire from the destroyers and the 155s allowed two rescue craft to dash for the beach and lift off the raiding group safely. With none of the original objectives achieved, the raid had been a costly failure, even though it had left at least 145 Japanese dead.