'Fall River' was the Allied programme to deliver reinforcements to and build airfields in the Milne Bay area of south-eastern Papua (June/July 1942).

Allied interest in the Milne Bay area began on 8 June, when a small Australian and US party arrived to reconnoitre the area for sites on which airfields could be established. The mission was successful, for on 12 June General Douglas MacArthur’s South-West Pacific Area command authorised the construction of airfields round the head of Milne Bay. A small Allied garrison (two companies and a machine gun platoon of Brigadier A. Jackson’s Australian 15^th Brigade) departed Port Moresby by sea on 22 June, bound for Milne Bay, which it reached three days later. This first echelon was followed on 29 June by Company E of the US 46^th Engineer Regiment, which began work on the new airfields. These were soon operational, and by the time the Japanese delivered their 'Re' attack on 25 August the Royal Australian Air Force’s Nos 75 and 76 Squadrons equipped with Curtiss P-40 Kittyhawk single-engined fighters, and No. 6 Squadron equipped with Lockheed Hudson twin-engined reconnaissance bombers, were all flying from the new airfields.

The garrison was dramatically increased in size before the Japanese arrived. During July Brigadier J. Fields’s Australian 7^th Brigade was ordered to Milne Bay where, on 21 August, it was joined by Brigadier G. F. Wootten’s 18^th Brigade, an experienced regular unit. Including the US engineers and the US 709^th Airborne Anti-Aircraft Battery, the garrison of Milne Bay before the start of 'Re' numbered around 8,700 soldiers and 664 airmen under the command of Major General Cyril A. Clowes.