On 4 September 1943, the Allies landed at Lae unopposed, and the 51st Division was ordered to reinforce the "Shoge detachment" of the 41st Division. 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.