One tree. That was all a U.S. cartographer saw on the crest of a coral ridge 6,000 feet west of the main jetty in Maffin Bay, and so one tree became the name of the place on every map that followed. The hill itself was tangled with tropical rainforest so dense that men crawling up its 175-foot slopes could not see ten yards ahead. Beneath that green skin, the Japanese 223rd and 224th Infantry Regiments had spent weeks carving fortified caves into the coral. In the summer of 1944, American soldiers would have to go in after them.
After Hollandia fell in late April 1944, a 26-mile stretch of coast around Toem, Wakde, and Sarmi was the only strip of Dutch New Guinea shoreline the Japanese still held with any strength. Lieutenant General Hachiro Tagami concentrated his men at Lone Tree Hill because it commanded everything. The ridge rose abruptly from a flat coastal plain, 3,600 feet long north to south, 3,300 feet wide east to west, with a steep northern face and a crooked little stream on its eastern flank that the Americans christened Snaky River. So long as Tagami held the high ground, the U.S. 158th Regimental Combat Team could not advance toward Sarmi, and the Allied push westward along the New Guinea coast stalled on a patch of coral the size of a small town.
On 14 June, General Walter Krueger sent the 6th Infantry Division in to relieve the exhausted 158th. What followed was not a battle of sweeping maneuver but of close, suffocating violence. The caves were the problem. Soldiers threw in grenades, satchel charges, flamethrowers, and still the fire came back. Ten days of hard fighting cracked the hill open piece by piece. More than a thousand Japanese soldiers died in those caves, some sealed inside by the collapse of their own shelters when demolitions brought the coral down. The Americans took about 700 battle casualties and 500 more from the fevers, dysentery, and infections that the jungle added free of charge. By 1 September, some 2,000 Japanese troops remained scattered in the area, but they no longer had the strength to threaten Allied operations. The hill was taken.
What made Lone Tree Hill worth the cost was what lay behind it. With the ridge in American hands, Maffin Bay could finally be developed as a major staging base. The jetty that the battle had been fought 6,000 feet away from became one of the busiest loading docks in the Southwest Pacific. From this small, unpromising anchorage on the Dutch New Guinea coast, the U.S. Army mounted the invasions of Biak, Noemfoor, and Sansapor in the following months, and then the far larger landings at Leyte and Luzon that finally pried the Philippines from Japanese control. Six major amphibious operations traced their start line back to Maffin Bay. The single tree on the coral crest, whose name had been chosen almost as a map-maker's joke, ended up marking one of the hinge points of the Pacific War.
The ridge is still there, still covered in the same dense rainforest, still unmarked on any mainstream tourist map. The coastline of what is now Papua, Indonesia remains thinly populated, and the coral outcrops around Sarmi look much as they did in 1944. Cave entrances collapsed by American demolitions have never been systematically surveyed; Japanese remains are occasionally still recovered by the Japanese Ministry of Health's overseas war dead repatriation program. From the air the hill blends into the general green of the coast, one small swell of land among thousands. Knowing what happened there changes how you see it.
Located at 1.20 S, 138.83 E, on the northern coast of Papua, Indonesia, overlooking Maffin Bay near Sarmi. Viewing altitude 3,000 to 5,000 feet gives the best sense of how the ridge commands the flat coastal plain. The closest active airport is Sarmi-Orai Airport (ZRM). Sentani Airport (DJJ/WAJJ) at Jayapura, about 200 km east, is the region's main hub. The equatorial coast is prone to afternoon thunderstorms; mornings typically offer the clearest visibility.