Operation Highjump (OpHjp), officially titled The United States Navy Antarctic Developments Program, 1946-1947, was a United States Navy operation organized by Rear AdmiralRichard E. Byrd Jr., USN (Ret), Officer in Charge, Task Force 68, and led by Rear Admiral Richard H. Cruzen, USN, Commanding Officer, Task Force 68. Operation Highjump commenced 26 August 1946 and ended in late February 1947. Task Force 68 included 4,700 men, 13 ships, and multiple aircraft. Operation Highjump's primary mission was to establish the Antarctic research base Little America IV.
Highjump’s objectives, according to the U.S. Navy report of the operation, were:
Training personnel and testing equipment in frigid conditions;
Consolidating and extending the United States' sovereignty over the largest practicable area of the Antarctic continent (This was publicly denied as a goal even before the expedition ended);
Determining the feasibility of establishing, maintaining, and utilizing bases in the Antarctic and investigating possible base sites;
Developing techniques for establishing, maintaining, and utilizing air bases on ice, with particular attention to later applicability of such techniques to operations in interior Greenland, where conditions are comparable to those in the Antarctic;
The Western Group of ships reached the Marquesas Islands on December 12, 1946, whereupon the Henderson and Cacapon set up weather monitoring stations. By December 24, the Currituck had begun launching aircraft on reconnaissance missions.
The Eastern Group of ships reached Peter I Island in late December 1946.
On January 1, 1947, LCDR Thompson and Chief Petty Officer Dixon utilized "Jack Browne" masks and DESCO Oxygen rebreathers to log the first dive by Americans under the Antarctic.Paul Allman Siple, Ph.D. was the senior U.S. War Department representative on the expedition. Dr. Siple was the same Eagle Scout who accompanied Admiral Byrd on the previous Byrd Antarctic expeditions.
On December 30, 1946, aviation radiomen Wendell K. Hendersin, Fredrick W. Williams, and Ensign Maxwell A. Lopez were killed when their PBM MarinerGeorge 1crashed during a blizzard. The surviving six crew members, including aviation radioman James H. Robbins and co-pilot William Kearns, were rescued 13 days later. A plaque was later erected at the McMurdo Station research base, honoring the three killed crewmen, and Mount Lopez, on Thurston Island, was named in honor of killed airman Maxwell A. Lopez.
In December 2004, an attempt was made to locate the remains of the plane. There are ongoing efforts to repatriate the bodies of the three men killed in the crash.
Sometime after December 30, 1946, Vance N. Woodall died during a "ship unloading accident". In a crew profile, deckman Edward Beardsley described his worst memory as "when Seaman Vance Woodall died on the Ross Ice Shelf under a piece of roller equipment designed to 'pave' the ice to build an airstrip."
Naval ships and personnel were withdrawn back to the United States in late February 1947, and the expedition was terminated due to the early approach of winter and worsening weather conditions.
Admiral Byrd, in an interview with Lee van Atta of International News Service aboard the expeditions command ship, the USS Mount Olympus, discussed the lessons learned from the operation. The interview appeared in the Wednesday, March 5, 1947 edition of the Chilean newspaper El Mercurio and read in part as follows:
Admiral Richard E. Byrd warned today that the United States should adopt measures of protection against the possibility of an invasion of the country by hostile planes coming from the polar regions. The admiral explained that he was not trying to scare anyone, but the cruel reality is that in case of a new war, the United States could be attacked by planes flying over one or both poles. This statement was made as part of a recapitulation of his own polar experience, in an exclusive interview with International News Service. Talking about the recently completed expedition, Byrd said that the most important result of his observations and discoveries is the potential effect that they have in relation to the security of the United States. The fantastic speed with which the world is shrinking – recalled the admiral – is one of the most important lessons learned during his recent Antarctic exploration. I have to warn my compatriots that the time has ended when we were able to take refuge in our isolation and rely on the certainty that the distances, the oceans, and the poles were a guarantee of safety.
After the operation ended, a follow-up Operation Windmill returned to the area, in order to provide ground-truthing to the aerial photography of Highjump, from 1947-1948. Finn Ronne also financed a private operation to the same territory, until 1948.
As with other U.S. Antarctic expeditions, interested persons were allowed to send letters with enclosed envelopes to the base, where commemorative cachets were added to their enclosures, which were then returned to the senders. These souvenir philatelic covers are readily available at low cost.
Helicopter landing on icebreaker USCGC Northwind during Operation Highjump
In Robert Doherty's Area 51 novel series Operation Highjump is said to have been a cover for an expedition to excavate flying saucers buried under Antarctica's ice shelf by long-ago extraterrestrial visitors.
Much of the action in James Rollins' novels Subterranean (1999) and The 6th Extinction: Sigma Force Book #10 (2014) takes place at the American base in the Antarctic and liberally reference Colonel Byrd and other nation's bases, expeditions, equipment, and artifacts. For example, in The 6th Extinction, the characters investigate the remains of a Nazi U-boat, discuss cryptic statements by Admiral Karl Dönitz during the Nuremberg trials and his light prison sentence, and some escape using Colonel Byrd's snow cruiser.
Adherents to the Hollow Earth hypothesis believe that Admiral Byrd flew over the North Pole and into the hollow earth in February 1947, and that he kept a secret diary of the incident. This belief was first published in F. Amadeo Giannini's book The Worlds Beyond the Poles: Physical Continuity of the Universe (1959). Giannini writes that Byrd encountered a humanoid being from another "world" who warned humanity to pursue peace and not war; he also reports that Byrd spotted a living woolly mammoth near the North Pole.
One major problem with Giannini's account is that in February 1947, Byrd was leading Operation Highjump in Antarctica and was, consequently, nowhere near the North Pole. Another problem is that in February the Arctic is in winter, and sunlight does not reach the North Pole, so it would have been impossible for Byrd to see something, like a woolly mammoth, from the air. Furthermore, Giannini quotes directly from the movie Lost Horizon (1937)  in the dialog of the humanoid Byrd allegedly encountered. Some Hollow Earth theorists believe that The Worlds Beyond the Poles was published by "controllers" in order to discredit the Hollow Earth theory.
A highly controversial, hour-long German "documentary", UFO — Technology Secrets and the Third Reich, suggests at the end of the film that the real purpose for Operation Highjump was to seek out a secret German UFO station still operating in the Antarctic; to find Nazis who had fled to Antarctica at the end of World War II and had established a secret base with submarines, aircraft, and flying saucers. The U.S. vessels the film mentions do not correspond with the facts: the U.S. lists neither the USS Casablanca, which was already decommissioned at the time, nor the USS Murdoch, allegedly sunk by a flying saucer, among the naval ships that participated in the mission. The allegation that 100 German U-boats also disappeared right before the end of the war is also unsubstantiated. No credible evidence has ever been found to support this theory.