Ninety miles long on a northwest-southeast axis and an average of twenty-five miles wide, Guadalcanal presented forbidding terrain of mountains and dormant volcanoes up to eight thousand feet high, steep ravines and deep streams, and a generally even coastline with no natural harbors.

With the invasion of Guadalcanal on 7 August, 1942, in the months of combat before the 25th Division arrived on Guadalcanal, the marines had waged a hard-fought battle, but by autumn few advances had been made. At the beginning of December the Americal Division relieved the exhausted 1st Marine Division who left the island. The 1st had been part of the initial assault, and besides combat casualties, had suffered from heavy malaria losses and other health problems. With the departure of the 1st Marine Division, no large scale offensives could be launched until the troops of the 25th arrived.

Maj. Gen. Millard Harmon, commanding U.S. Army Forces in the South Pacific, determined that a limited offensive against Mount Austen, the high ground which dominated the American positions around Henderson Airfield and Lunga Point, was necessary for further advance. Maj. Gen. Alexander Patch, appointed January 2 as the newly formed XIV Corps commander, agreed and planned the assault. After limited success in the attack, the Americal's 132d Infantry held positions on the hill to the northwest of Mount Austen. All preparations were complete for the January offensive.

In November the 25th Division was ordered to Guadalcanal as part of the relief of the 1st Marine Division. On the 25^th, the 35^th Infantry Regiment left Oahu on the first of three convoys transporting the 25th Infantry Division, arriving on 17 December, 1942. By the end of the first week in January, all three regimental combat teams (RCTs) of the 25th had arrived on Guadalcanal.

While the 27th Infantry had been making spectacular gains over the open hills of the Galloping Horse, the 35th Infantry of the 25th Division was heavily engaged in its zone, which included Mount Austen and the hilly, juggled areas south of the southwest Matanikau fork. Except for the open hills previously taken by the 132d Infantry, there was only one extensive piece of open ground in the 35th's zone. This ground, formed by Hills 43 and 44, was named the Sea Horse from its appearance in an aerial photograph.

Lying about 1,500 yards northwest of Hill 27 and about 1,500 yards east of the objective line, the Sea Horse dominated the low ground along the Matanikau. As capture of the Sea Horse would bottle the Japanese along the Matanikau and its forks, the 35th Infantry decided to capture the Sea Horse first, and then to advance to the objective in its zone. Like the Galloping Horse, the Sea Horse is also isolated by river forks, deep canyons, and solid jungle. The best route to the Sea Horse lay over Mount Austen, south of the Gifu, and through the jungle to the south end of Hill 43.

The task of the 35th Infantry in the Corps offensive was fourfold: to relieve the 132d Infantry at the Gifu, to capture the Sea Horse, to cover the Corps' left flank, and to push west to seize and hold the objective in its zone, a line south of the head of the Galloping Horse about 3,000 yards west of Mount Austen. For this operation the 3d Battalion of the 182d Infantry, commanded by Lt. Col. Roy F. Goggin, and the 25th Division's Cavalry Reconnaissance Troop were attached to the 35th Infantry.

Colonel McClure, commanding the 35th Infantry, ordered the 2d Battalion and the Reconnaissance Troop to relieve the 132d Infantry at the Gifu and to press against that strong point and keep in touch with Goggin's battalion on the right. The 3d Battalion, commanded by Lt. Col. William J. Mullen, Jr., was to advance southwest from Hill 27 (south of the Gifu on Mount Austen), and then swing north to seize Hills 43 and 44. Lt. Col. James B. Leer's 1st Battalion was to be initially in regimental reserve, following about a half day's march behind the 3d Battalion. The 3d Battalion, 182d Infantry, was to protect the 25th Division's artillery positions on the open ground north of Mount Austen and east of the Matanikau by advancing south from Hill 65 to block the river gorge and the ravine between Hills 31 and 42 against Japanese infiltration. The battalion was to maintain contact with the 27th and 35th Regiments on either flank. (1)

The 35th Infantry's attacks, if successful, would pocket the enemy in the Gifu and in the ravines and valleys of the Matanikau forks. The 3d Battalion, by attacking the Sea Horse from the south, would attempt to encircle the right flank of the Japanese and cut off their lines of supply and retreat. The final movement of the 35th Infantry west from Hill 43 to the objective, where the southeast Matanikau fork cuts southward, would complete the trap.

Taking of the Sea Horse

Advancing to their lines of departure was considerably more difficult for the battalions of the 35th Infantry than for those of the 27th. The 35th Infantry, having pulled out of the Lunga perimeter defense on 7 January, the next day marched up Wright Road to Mount Austen in column of battalions, with the 3d Battalion leading. While the 2d Battalion moved into line at the Gifu, the 3d Battalion, followed by the 1st, cut south and west through the jungle south of the Gifu to bivouac for the night of 8-9 January on a small ridge about 700 yards south of Hill 27. (Map XVII) The mortar sections of these battalions remained at the Gifu, but the light machine guns were carried along during the advance.

The next day the 3d Battalion marched over slippery ravines and ridges to its line of departure, a small knoll about 1,500 yards southwest of Hill 27, and about 2,000 yards southeast of Hill 43. The 1st Battalion moved west to occupy the bivouac held by the 3d Battalion on the previous night. These movements were made in secret, for success of the 3d Battalion's attack depended upon surprise. To avoid warning the enemy of the impending attack, there were to be no preliminary artillery or aerial bombardments in the 35th Infantry's zone.

From the 3d Battalion's bivouac area Colonel Mullen was able to see a small wooded hill, a short distance south of Hill 43. From direct observation and photographic study he concluded that a narrow ridge connected the small hill with Hill 43. He decided to capture the small hill first since it would provide a good route to the grassy slopes of Hills 43 and 44. (2) At H Hour, 0635 of 10 January 1943, while the 27th Infantry was beginning its attack, the 3d Battalion began its envelopment. Fearing that the enemy might have observed his troops, Colonel Mullen kept I Company, the battalion reserve, spread out over the bivouac area to deceive the Japanese while the assault companies, K and L, formed in the dense woods prior to attacking. By 0800 K and L Companies were ready to move. (3) Patrols on the previous night had reconnoitered in front of the bivouac area to feel out the Japanese. Relying on data from these patrols, the battalion pushed southwest through the jungle. Advancing in column of companies, the battalion then turned north toward the Sea Horse. K Company, leading, cut a trail for about 1,000 yards with machetes and bayonets, but its route led it down onto low ground along a branch of the Matanikau. At noon it reached a small knoll about 700 yards southeast of Hill 43. The company was then on ground that was dominated by ridges and bluffs on all sides.

The battalion had turned northward too soon, and it was now southeast instead of southwest of Hill 43. The assault companies had to advance farther west before they could envelop the south flank of the Sea Horse. (4) As hills, deep ravines, and a branch of the Matanikau lay between K Company and Hill 43, patrols advanced to the west and northwest, and one found a faint trail that led westward.

The 35th Infantry then requested that artillery fire be placed on the Sea Horse. At 1300 the battalion commander ordered K Company to advance over the west trail. L Company, also following an old trail, was to advance on K's left. I Company, which had been relieved at the line of departure by the 1st Battalion, was to follow the assault company that found the best route. Colonel Mullen, who wished his battalion to reach the greater security of high ground before dark, ordered that the advance be pressed vigorously.

As the assaulting American companies were advancing to the west, K Company surprised a Japanese supply party near a water hole at the junction of two trails, killed seven, and dispersed the rest. (7) Having then reached a point about due south of Hill 43, the companies swung northward toward their preliminary objective, the wooded hill south of Hill 43. Only a few scattered Japanese were in front, and they failed to offer any effective opposition. By 1700 K and L Companies had reached high ground 400 yards south of the open slopes on Hill 43. As dusk was falling rapidly, the 3d Battalion, which to gain high ground had kept moving much later in the afternoon than was considered advisable in the jungle, halted and hastily dug in for the night. (8)

While the 3d Battalion was advancing toward the Sea Horse, Colonel Leer's 1st Battalion, in reserve, moved farther west. Patrols from A and C Companies covered the right and left flanks. Platoons of B and D Companies relieved I Company at the water hole in a gulch about 600 yards south of Hill 43.

Colonel Mullen's battalion resumed the attack against the Sea Horse at dawn on 11 January. K Company led the attack north along the ridge toward Hill 43, while L Company covered the left flank and I followed in reserve. The progress of K Company was slow against enemy machine gunners who fired to delay the attack, then fell back to new positions. In one hour it gained only 100 yards. (9) The advance gathered speed later in the afternoon, however, and the 3d Battalion emerged from the jungle, drove the enemy off Hill 43, and by 1831 had advanced to Hill 44. (10)

Meanwhile Colonel Leer's battalion had come forward to assist the 3d Battalion when its advance was retarded. But when K Company cleared Hill 43, and it became evident that the 3d Battalion would reach its objective unaided, Colonel McClure ordered the 1st Battalion to relieve I and L Companies on the south and southwest wooded parts of Hill 43. When relieved those companies joined the remainder of the 3d Battalion on the Sea Horse. (11) By nightfall on 11 January, the 35th Infantry had completed the encirclement of the Gifu on the east and west by seizing the Sea Horse, and had progressed halfway toward its objective, about 1,500 yards west of the Sea Horse.

 percent of the food was usable, but only 15 percent of the ammunition could be used, and nearly all the 5-gallon water cans were ruined. Regular ground supply was not resumed until 17 January when the Pusha Maru reached the foot of Hill 50, and carriers began hauling supplies up the north slopes of Hill 44. (12)

When L and I Companies had reached the Sea Horse Colonel Mullen organized a perimeter defense, with L Company holding Hill 44, I Company the narrow neck between 44 and 43, and K Company, Hill 43. On the morning of 12 January the 3d Battalion made contact with the forces which had just taken the eastern half of the Galloping Horse. (13)

Colonel Leer's 1st Battalion assumed the brunt of the attack west to the objective on 12 January. (Map 11) B Company defended the hill south of Hill 43, A Company the water hole, while C Company attacked along a narrow ridge southwest of Hill 43. Enemy fire from a ridge about 150 yards to the southwest halted the advance. (14)

While patrols from C Company were seeking the enemy flanks, an enemy force from east of Hill 43 struck just south of Hill 43 against the supply trail and isolated the 3d Battalion on the Sea Horse. At 1730 one B Company platoon counterattacked and by nightfall it had recaptured the trail.

Japanese rifle fire again stopped C Company on 13 January. The 64th Field Artillery Battalion meanwhile continued registration on enemy targets, and Colonel Leer asked regimental headquarters to send forward to Hill 43 the mortars which were then on Mount Austen under regimental control.

Operations on 14 January again failed to gain ground. C Company attacked the enemy ridge twice without success. The terrain slowed the movement of the mortars, which failed to reach Hill 43 until late afternoon. In the afternoon, however, one of Colonel Leer's patrols found a route around the enemy's right flank.

The next morning B Company relieved C Company. The 64th Field Artillery Battalion then fired 553 rounds on the Japanese on the ridge in a 30-minute concentration ending at 1005, (15) followed by fire from machine guns and mortars.

When the artillery ceased firing B Company, reinforced by one platoon from D, moved around the enemy's right flank and struck him in the rear. B Company killed thirteen Japanese and captured twelve prisoners; it also took two 70-mm. guns, three light machine guns, and a quantity of ammunition. B Company had penetrated an enemy bivouac area with room for an estimated 1,000 troops. It was then occupied by one platoon. The platoon had no rations; six of the prisoners were too weak to walk, and there were seventy-eight graves in the area. (16) Since daylight was ending, B Company halted for the night. The defunct enemy platoon had been the only effective enemy force between the Sea Horse and the objective in the 35th Infantry's zone. The next day, 16 January, B Company and the reinforcing platoon from D Company moved west to the objective without fighting. About 1500 they reached a precipice overlooking the southwest fork of the Matanikau. So dense was the jungle that the troops could not determine their exact location until the next day, and on 18 January they built smoky fires and fired amber flares to reveal their location to the 25th Division observation posts. (17)

In capturing the Sea Horse and advancing to the Matanikau, the 1st Battalion reported that it had killed 144 of the enemy; the 3d Battalion, 414. Enemy prisoners totaled 17 for both battalions. The 3d Battalion had captured 35 light and heavy machine guns, the 1st Battalion, 9 light machine guns. The 1st Battalion had also captured 112 rifles and 18 pistols, while the 3d Battalion took 266 rifles and 26 pistols. (18) In the days following the capture of Hills 43 and 44 the 3d Battalion reduced a pocket of Japanese along the Matanikau just east of Hills 43 and 44. (19) The capture of the Sea Horse and the advance to the Matanikau had covered the XIV Corps' left (south) flank, and brought the 35th Infantry up to the objective on the left (south) of the 27th Infantry.