The other half of the 4th Raider Battalion (Companies N and Q) received its baptism of fire during this same period. This unit was under command of the battalion executive officer, Major James R. Clark. It was assigned to assist the Army’s 2d Battalion, 103d Infantry (Lieutenant Colonel Lester E. Brown) in seizing Vangunu and the approaches to Wickham Anchorage on 30 June. Intelligence from the coastwatchers indicated that there were about 100 Japanese occupying the island. The plan called for the raiders to make a pre-dawn landing at undefended Oloana Bay. The Army would follow them ashore after daylight, establish a beachhead, and then deal with the enemy, thought to be located in a village along the coast several miles to the east.
The night landing under conditions of low visibility and heavy seas turned into a fiasco. The APDs began debarkation in the wrong spot, their Higgins boats lost formation when they attempted to pass through the LCIs loaded with soldiers, and the two raider companies ended up being scattered along seven miles of coastline. When the Army units began to land after daylight, they found just 75 Marines holding the designated beachhead. A two-man patrol (one lieutenant each from the raiders and the Army battalion) had been ashore since mid-June to reconnoiter with the aid of native scouts. They provided the exact location of the Japanese garrison, and the joint force soon headed to the northeast toward its objective. Native scouts and the handful of Marines led the way, with two Army companies (F and G) in trace. The remaining raiders were to join up with their unit as soon as they could. All but one platoon did catch up by the time the Americans reached their line of departure a few hundred yards north of the village. The plan of attack was simple. The Army units passed through the raiders on the east-west trail to assume the easternmost position. The entire column of files then merely faced to the right, which placed the composite battalion on line and pointing toward the enemy to the south. Company Q held the right flank on the bank of the Kaeruka River. Company N in the center and Company F on the left flank would guide on the movements of Q. Company G held back and acted as the reserve. Within minutes of beginning the advance, the attack ran into resistance. Japanese fire from the west bank of the river was particularly heavy and Company Q crossed over to deal with this threat. At the same time Company F moved to its left to skirt around strong defenses. Company G soon moved in to fill the gap. By late afternoon the Americans were able to clear the east bank of the river. Lieutenant Colonel Brown ordered Company Q to disengage from the west bank and join in the battalions perimeter defense at the mouth of the river. The Marines had lost 10 dead and 21 wounded, while the Army had suffered similarly.
The enemy made no ground attack that night, but periodically fired mortars and machine guns at American lines. During a lull at 0200 three Japanese barges approached the beach, apparently unaware that ownership of the real estate was under dispute. As they neared shore, the Marines guarding the seaward portion of the perimeter opened up. One craft sank and the other two broached in the surf. Two Marines and one soldier died in the firefight, but the entire enemy force, estimated at 120 men, was destroyed in the water or on the beach.
The next morning Brown decided to disengage and move to Vura Village, where he could reorganize and direct fire support on the remaining enemy at Kaeruka prior to launching another attack. The Americans received only harassing fire as they withdrew. After a day of preparatory fire by air, artillery, and naval guns, the composite battalion returned to Kaeruka on 3 July. They seized the village against minimal resistance, killed seven more Japanese, and captured one. The raiders returned to Oloana Bay by LCI later the next day. On 9 July they made a pre-dawn landing from an LCT on Gatukai Island to investigate reports of a 50-man Japanese unit. The Marines found evidence of the enemy but made no contact. They returned to Oloana Bay on 10 July and departed for Guadalcanal the day after. There they joined up with Lieutenant Colonel Currin and the rest of the 4th Raider Battalion.