In April 1939, aware of the stirrings in Europe, Feldt transferred back to the Navy's emergency list. When war came in September 1939, the Director of Naval Intelligence, Commander Rupert Long, a 1913 naval classmate, offered Feldt the task of heading a new Naval Intelligence Centre in
Port Moresby. From there Feldt could vastly extend the existing, but small, Coastwatcher service in
Papua New Guinea and the
Solomon Islands. Feldt accepted the position. In that same month Feldt set out to travel in New Guinea, Papua and the Solomons to personally enlist the help of every man who had a teleradio. "My travels took me all around the area by ship, motor boat, canoe, foot, bicycle and aeroplane, so I saw nearly everybody and nearly everybody saw me…… and nearly all were helpful." At this stage all Feldt's appointments were unpaid civilian volunteers. A teleradio consisted of a transmitter, a receiver and a loud speaker, which were transported in three metal boxes measuring 60 cm x 30 cm x 30 cm. They were powered by car batteries, which were charged by a petrol engine weighing 30 kg. Moving them was difficult, requiring 12–16 indigenous people to help carry them. The Coastwatchers headquarters was moved to
Townsville in May 1941. When the
War in the Pacific commenced at the end of 1941, Feldt's responsibilities for his Coastwatchers increased, as the Japanese advance left the island screen as the front line. He insisted the Coastwatchers be given military standing which would provide them some income and protection for their widows via a pension, should the worst outcome occur. In April 1942 the Coastwatchers became members of the
Royal Australian Naval Volunteer Reserve (RANVR). By this time many of them were behind enemy lines. As Supervising Intelligence Officer (SIO), Feldt's duties were varied and demanding. As well as evaluation of intelligence, coding and de-coding, many other practical issues required overseeing. These included organising supplies such as food, uniforms, radio parts and parachutes to drop the latter, arranging finance for the supplies and organising submarines, PT boats and aircraft to retrieve downed airmen, sailors and coastwatchers who were ill or injured and placing new coastwatchers in their stead. To Feldt, the needs of his coastwatchers were first and foremost. They, in turn, were extremely loyal to him. He worked for long hours throughout 1942 and into 1943. He suffered the loss of his best friend, Bill Kyle, whom he had recruited as a coastwatcher. Kyle was captured and executed by the Japanese. The Coastwatchers made many significant contributions to the war in the Pacific but none more so than in the
Battle for Guadalcanal. Messages from Read and Mason, such as "24 bombers headed yours" gave the American fighter aircraft a distinct advantage with time to be in the air as a "welcoming party" for the Japanese planes. This happened many times over and was of such significance that US Admiral of the Fleet
William F. "Bull" Halsey said: "The coast watchers saved the Guadalcanal and Guadalcanal saved the South Pacific." Besides their vital intelligence gathering, the Coastwatchers rescued 321 downed Allied airman, 280 sailors, 75 prisoners of war, 190 missionaries and civilians. The responsibility and demands of leadership eventually took its toll on Feldt. While making a personal visit to some of his Coastwatchers in Guadalcanal in 1943, he suffered a heart attack, at the age of 44, and resigned his command. Commander J. C. McManus succeeded Feldt. While recuperating in Brisbane in 1943, Feldt commenced writing his personal account. His book
The Coast Watchers was published in 1946. ==Post War==