Battle of Sio

Australian troops of B Company, 30th Infantry Battalion crossing a shallow creek between Weber Point and Malalamai. They have been advancing from Roinji over muddy swamps, Kunai grass and innumerable rivers to link up with American troops at Yagomai.

Date	5 December 1943 – 1 March 1944
Location	Sio, Papua New Guinea
Result	Allied victory

Belligerents

Australia

Papua

United States

Empire of Japan

Commanders and leaders

Strength

~15,000

~8,000

Casualties and losses

83 killed, 186 wounded.

1,421 killed, 2,198 found dead, 76 captured.

Australia

The Battle of Sio, fought between December 1943 and March 1944, was the break-out and pursuit phase of General Douglas MacArthur's Huon Peninsula campaign, part of the New Guinea campaign of World War II.

After the defeat of the Japanese in the Battle of Sattelberg, Australian Army forces broke through the Japanese positions around Finschhafen. Constant pressure from US Navy PT boats, Australian land forces and Allied aircraft brought the Japanese logistical system to the brink of collapse, resulting in disease, malnutrition and privation for the Japanese soldiers. Meanwhile, the Allied supply system grappled with the problems of terrain and climate, particularly inclement weather and rough monsoonal seas that hampered and occasionally prevented delivery of supplies by sea.

Australian and Papuan troops advanced along the coast of the Huon Peninsula, using infantry, tanks, and air strikes against the Japanese positions, which were generally sited at creek crossings in the jungle. The advancing infantry kept strictly within range of the supporting artillery, which was liberally employed in the early stages of the operation. Using tactics that exploited the firepower of Australian artillery and armour, the Australian and Papuan troops inflicted heavy and disproportionate casualties on the Japanese as they advanced, ultimately linking up with the American forces at Saidor. Hundreds of Japanese soldiers were killed; thousands more died from disease, malnutrition, exhaustion and suicide. The Allies failed to seize the opportunity to completely destroy the Japanese forces.

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