The Araki detachment of the 51st division, consisting of the 66th Infantry Regiment was used that time for the rearguard duties in Battle of Hong Kong.

Meanwhile, the rest of the 51st Division reached Lae in May 1943 having moved there in several landing craft following the New Guinea coast from Madang or from the Dampier Strait.

On 8 September 1943, the Hidemitsu Nakano ordered a general retreat from Salamaua to Lae due to the threat of imminent encirclement by Allied forces advancing inland after Landing at Nadzab.

By this time, an order was received to evacuate to the north coast of Huon Peninsula, therefore the 51st Division tried to cross the Saruwaged Range, which proved to be nearly impassable.

The division lost all of their heavy equipment and most of their rifles due exhaustion and hunger, and the passage took a whole month instead of expected ten days.

Due to a lack of weapons and ammunition, the survivors of the 51st Division were largely excluded from the Huon Peninsula campaign, with only one left-behind company from the 102nd Infantry Regiment participating in the Battle of Finschhafen.