Coastwatchers

The Coastwatchers, also known as the Coast Watch Organisation, Combined Field Intelligence Service or Section C, Allied Intelligence Bureau, were Allied military intelligence operatives stationed on remote Pacific islands during World War II to observe enemy movements and rescue stranded Allied personnel. They played a significant role in the Pacific Ocean theatre and South West Pacific theatre, particularly as an early warning network during the Guadalcanal campaign.
Overview.
Captain Chapman James Clare, district naval officer of Western Australia, proposed a coastwatching programme in 1919.
The Australian Commonwealth Naval Board first established the coastwatching organisation, operated through the Naval Intelligence Division, in 1922. Originally confined to Australia, it expanded after the outbreak of war in 1939 to New Guinea and to the Solomon Islands. About 400 coastwatchers served in total—mostly Australian military officers, New Zealand servicemen, Pacific Islanders, or escaped Allied prisoners of war.
Lieutenant Commander Eric Feldt, based in Townsville, Queensland, led the Australian coastwatch organisation during much of World War II. Coastwatchers became particularly important in monitoring Japanese activity in the roughly one thousand islands that make up the Solomon Islands. Commander Feldt resigned his command due to illness in March 1943. His role was taken over by James McManus of the Royal Australian Navy.
The Australian military commissioned many personnel who took part in coastwatcher operations behind enemy lines as officers of the Royal Australian Navy Volunteer Reserve (RANVR) to protect them in case of capture, although the Imperial Japanese Army did not always recognise this status, and executed several such officers. Escaped Allied personnel and even civilians augmented the coastwatchers' numbers. In one case, three German missionaries assisted the coastwatchers after escaping Japanese captivity, even though Nazi Germany had allied itself with the Empire of Japan during the war.
Feldt code-named his organisation "Ferdinand", taking the name from a popular children's book about a bull, "The Story of Ferdinand". He explained this by saying:
In June 1942 "Ferdinand" became part of the Allied Intelligence Bureau, which came under the Allies' South West Pacific Area (command) (SWPA). However Feldt reported both to GHQ, SWPA, in Brisbane and to the United States-Australian-British Fleet Radio Unit in Melbourne (FRUMEL), which came under the Pacific Ocean Areas command.
New Zealand developed its own coastwatching scheme from the 1930s. From the outbreak of war, the New Zealand Naval Board controlled coastwatching stations located around the New Zealand coastline and in the eastern Pacific. Stations were established in the Gilbert and Ellice Islands, Tokelau, Samoa, Fanning Island, the Cook Islands, Tonga, and Fiji. For the coastwatching programme in New Zealand's sub-Antarctic islands from 1941 to 1945, see Cape Expedition.
Significance.
In early November 1942, two coastwatchers named Jack Read and Paul Mason on Bougainville Island radioed early warnings to the United States Navy about Japanese warship and air movements (citing the numbers, type, and speed of enemy units) preparing to attack the US Forces in the Solomon Islands. 
One of the most highly decorated coastwatchers was Sergeant Major Sir Jacob C. Vouza, who retired from the local constabulary in 1941, volunteered for coastwatcher duty, and was captured and interrogated brutally. He survived and escaped to make contact with US Marines warning them of an impending Japanese attack. He recovered from his wounds and continued to scout for the Marines. He was awarded the Silver Star and Legion of Merit by the United States, and later received a knighthood as well as becoming a Member of the Order of the British Empire.
In 1943 Lt. (j.g.) John F. Kennedy of the United States Navy—a future President—and 10 fellow crew members were shipwrecked after the sinking of their boat, the "PT-109". An Australian coastwatcher, Sub-Lt Arthur Reginald Evans, observed the explosion of the "PT-109" when it was rammed by a Japanese destroyer. Despite US Navy crews giving up the downed crew as a complete loss, Evans dispatched Solomon Islander scouts Biuku Gasa and Eroni Kumana in a dugout canoe to search for survivors. The two scouts found the men after searching for five days. Lacking paper, Kennedy scratched a message on a coconut describing the plight and position of his crew; Gasa and Kumana then paddled through Japanese-held waters, at great personal risk, to deliver the message to Evans, who radioed the news to Kennedy's squadron commander. The future US President was rescued shortly afterward, and 20 years later welcomed Evans to the White House. Gasa did not make the trip, later claiming he received the invitation to attend but was fooled into not attending by British colonial officials. Gasa left his village and arrived in Honiara, but was not allowed to leave in time for the ceremony.
"After the rescue Kennedy said he would meet us again," Kumana says in "The Search for Kennedy's PT-109". "When he became President, he invited us to visit him. But when we got to the airport, we were met by a clerk, who said we couldn't go—Biuku and I spoke no English. My feelings went for bad."
When the Japanese overran the Gilbert Islands in 1942, 17 New Zealand coastwatchers were captured. Imprisoned at Tarawa, they were executed by the Japanese in October 1942 following an American air raid.
Cape Expedition.
From 1942 to 1945, New Zealand scientists were stationed on sub-Antarctic islands during World War II (to prevent their use as refuges by German surface raiders). The sinking of the British (but British and New Zealand crewed) ship "Turakina" by a German raider in the Tasman Sea is said to have given the notion priority for execution as those taken prisoner and then released described being taken to a harbour with snow and tussock. The idea was that scientists would not become bored but pursue their research. The stationing of the scientists was known for security reasons in scientific publications that ensued as the "Cape Expedition". The organizers of the expedition included Robert Falla, who later became an eminent New Zealand scientist.