The Allies continued to develop the base area at Milne Bay in support of the counter-offensive along the northern coast of Papua and New Guinea.
The American base became US Advanced Sub Base A on 21 April 1943, US Advance Base A on 14 August and US Base A on 15 November.
Its Australian counterpart, the Milne Bay Base Sub Area, was formed on 14 June 1943.
Two 155-millimetre (6.1 in) coastal guns with searchlights were provided to protect the base from naval threats.
New roads were built and the existing ones upgraded to make them passable in the wet conditions.
A meteorological record was set on 29 April 1944, when 24 inches (610 mm) of rain fell in a 24-hour period.
By June 1944, there was over 100 miles (160 km) of road in the area.

A bitumen-surfaced second runway was built at No.
1 Airstrip by No.
6 Mobile Works Squadron RAAF, after which the original runway was only used for emergencies and taxiing.
The minefield around No.
3 Airstrip was lifted and the airstrip was completed, with revetments and hardstands for 70 medium bombers.
A new wharf, known as Liles' wharf after the American engineer who supervised its construction, was built in September and October 1942.
This was capable of handling Liberty ships.
Henceforth ships could sail direct to Milne Bay from the United States, reducing the pressure on Australian ports and saving two or three days' sailing time in addition to the time formerly taken to unload and then reload the cargo on smaller ships in those ports.
PT boats were based at Milne Bay from December 1942, with PT boat overhaul facilities, a destroyer base, a transshipment and staging area and a Station Hospital also constructed.

On 14 April 1943, the Allied base was attacked by 188 Japanese aircraft during the Japanese air offensive, Operation I-Go.
The base's anti-aircraft defences were limited, but a force of 24 RAAF Kittyhawk fighters were on hand to respond to the attack.
Minor damage was inflicted on the supply dumps around the airfields, while one British motorship, Gorgon, was damaged and Van Heemskerk, a Dutch transport carrying US troops was sunk.
At least three Allied aircraft were shot down, while the Japanese lost seven aircraft.
Later, Milne Bay was used as a staging area for mounting the landing at Lae in September 1943, and the New Britain Campaign in December.
The base at Milne Bay remained operational until the end of the war.
The Allies continued to develop the base area at Milne Bay in support of the counter-offensive along the northern coast of Papua and New Guinea. The American base became US Advanced Sub Base A on 21 April 1943, US Advance Base A on 14 August and US Base A on 15 November. Its Australian counterpart, the Milne Bay Base Sub Area, was formed on 14 June 1943. Two 155-millimetre (6.1 in) coastal guns with searchlights were provided to protect the base from naval threats. New roads were built and the existing ones upgraded to make them passable in the wet conditions. A meteorological record was set on 29 April 1944, when 24 inches (610 mm) of rain fell in a 24-hour period. By June 1944, there was over 100 miles (160 km) of road in the area.
A bitumen-surfaced second runway was built at No. 1 Airstrip by No. 6 Mobile Works Squadron RAAF, after which the original runway was only used for emergencies and taxiing. The minefield around No. 3 Airstrip was lifted and the airstrip was completed, with revetments and hardstands for 70 medium bombers. A new wharf, known as Liles' wharf after the American engineer who supervised its construction, was built in September and October 1942. This was capable of handling Liberty ships. Henceforth ships could sail direct to Milne Bay from the United States, reducing the pressure on Australian ports and saving two or three days' sailing time in addition to the time formerly taken to unload and then reload the cargo on smaller ships in those ports. PT boats were based at Milne Bay from December 1942, with PT boat overhaul facilities, a destroyer base, a transshipment and staging area and a Station Hospital also constructed. 
On 14 April 1943, the Allied base was attacked by 188 Japanese aircraft during the Japanese air offensive, Operation I-Go. The base's anti-aircraft defences were limited, but a force of 24 RAAF Kittyhawk fighters were on hand to respond to the attack. Minor damage was inflicted on the supply dumps around the airfields, while one British motorship, Gorgon, was damaged and Van Heemskerk, a Dutch transport carrying US troops was sunk. At least three Allied aircraft were shot down, while the Japanese lost seven aircraft. Later, Milne Bay was used as a staging area for mounting the landing at Lae in September 1943, and the New Britain Campaign in December. The base at Milne Bay remained operational until the end of the war.
Battle of Milne Bay