The Landing at Scarlet Beach (Operation Diminish) (22 September 1943) took place in New Guinea during the Huon Peninsula campaign of the Second World War, involving forces from Australia, the United States and Japan. Allied forces landed at Scarlet Beach, north of Siki Cove and south of the Song River, to the east of Katika and about north of Finschhafen. The capture of Finschhafen allowed the construction of air base and naval facilities to assist Allied air and naval forces to conduct operations against Japanese bases in New Guinea and New Britain.