Operation Highjump – Emergency Withdrawal Operation Highjump was one of the largest military missions ever sent to Antarctica, carried out by the U.S. Navy between 1946 and 1947 under the leadership of Admiral Richard E. Byrd. Publicly presented as a training and scientific expedition, the mission was expected to continue for several months. Instead, it ended suddenly and far ahead of schedule, with ships and aircraft ordered to withdraw without a detailed public explanation, raising questions a