Photo By Lori Stewart | U.S. Army soldiers move east from the beachhead at Aitape, New Guinea, into the jungle...... read more read more
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by Lori S. Stewart, USAICoE Command Historian
JAPANESE SURPRISE AMERICAN FORCES AT AITAPE
About 2350 on 10 July 1944, ten thousand Japanese soldiers of the 18th Army streamed across the Driniumor River east of Aitape, New Guinea, and attacked thinly dispersed American positions. While signals intelligence had provided clear indications of the pending attack, outnumbered American forces were surprised and forced to fight a forty-five-day battle to restore their lines.
On 22 April 1944, American forces landed on the coast of Papua New Guinea near Hollandia in Operation RECKLESS and near Aitape, 120 miles to the east, in Operation PERSECUTION. These successful amphibious landings forced the Japanese to a new defensive line 520 miles to the west and isolated the Japanese 18th Army at Wewak nearly one hundred miles east of Aitape. Effective intelligence operations by Gen. Douglas MacArthur’s Southwest Pacific Area (SWPA) G-2, Brig. Gen. Charles A. Willoughby, and his staff provided the foundation for the American victory. Willoughby benefitted greatly from the capture of the entire code library of a Japanese division in mid-January. This had allowed the Central Bureau, SWPA’s signal intelligence organization operating out of Brisbane, Australia, to read thousands of Japanese messages that yielded order of battle data. The intelligence from these sources was referred to as ULTRA. [See This Week in MI History #37 22 April 1944 and #169 19 January 1944]
Soon after the Allied landings, Lt. Gen. Hatazo Adachi realized his 18th Army could not survive at Wewak without resupply and reinforcement. The Japanese commander decided to move his force westward to Aitape to seize Allied food and supplies to sustain his men until they could reach the rest of the Japanese force at the western end of the island.
Throughout the months of May and June, Allied forces were alerted to Adachi’s movements and intentions. On several occasions, patrols from the 32d Infantry Division in Aitape encountered some of Adachi’s long-range reconnaissance platoons looking for American dispositions in the area. Allied pilots sighted Japanese forces moving towards Aitape along a series of well-worn trails through the thick jungle. Captured documents and interrogations of prisoners added to the growing body of intelligence about Adachi’s approach.
By far, the most significant intelligence came from the continued interception of radio traffic from Adachi to his higher headquarters. A 28 May message first indicated Adachi’s intent to move on Aitape, and several subsequent messages detailed 18th Army’s preparations for the attack. One of the most critical messages, intercepted on 24 June, identified the Japanese routes of advance towards lightly manned American positions on the Driniumor River, fifteen miles east of Aitape, and revealed the enemy attack of 20,000 men would begin about 10 July.
As clear as the 24 June message appeared to be, subsequent messages muddied the picture by giving several alternate dates for the attack. When these days passed quietly, American forces relaxed. General Willoughby consistently believed the weakened condition of the Japanese forces would prevent them from carrying out any attack. On 10 July, postulating Adachi was temporarily delayed while he built up his supplies, he reported, “[P]resent patrol activity would not seem to point to the date of the attack being close at hand.”
Adachi’s force, however, crossed the shallow 300-foot-wide Driniumor right on schedule that night. Surprised and outnumbered American infantry and artillery killed many as they crossed. Yet, even in a feeble state from miles of march on nearly non-existent rations, the Japanese soldiers breached American lines. The resulting battle lasted forty-five days before the Americans restored the line and Adachi and his remaining men melted back into the dense jungle.
Several months after the battle, the Central Bureau highlighted the “outstanding intelligence” it had furnished leading up to the battle and reported, “…G-2 has said that never has a commander gone into battle knowing so much about the enemy as did the Allied commander at Aitape on 10-11 July 1944.” Even with such detailed intelligence, the resolve and desperation of Adachi’s men caught the Americans by surprise and off guard.
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| Date Taken: | 07.08.2024 |
| Date Posted: | 07.08.2024 10:45 |
| Story ID: | 475679 |
| Location: | US |
| Web Views: | 58 |
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