Fleet admiral (abbreviated FADM), officially known as "Fleet Admiral of the United States Navy", is a five-star flag officer rank in the United States Navy.
 Fleet admiral ranks immediately above admiral and is equivalent to General of the Army and General of the Air Force.
 Although it is a current and authorized rank, no U.S. Navy officer presently holds it, with the last living U.S. Navy fleet admiral being Chester W. Nimitz, who died in 1966.
John "Jack" Roland Redman (January 31, 1898 – May 29, 1970) was an admiral in the United States Navy.
 A naval communications officer, he played key roles in signals intelligence during World War II in Washington, D.C., and on the staff of Admiral Chester W. Nimitz.
The United States Fleet was an organization in the United States Navy from 1922 until after World War II.
 The acronym CINCUS, pronounced "sink us", was used for Commander in Chief, United States Fleet.
 This was replaced by COMINCH in December 1941, under , when it was redefined and given operational command over the Atlantic, Pacific, and Asiatic Fleets, as well as all naval coastal forces.
 authorized the offices of the CNO and COMINCH to be held by a single officer; Admiral Ernest J. King was first to do so, and 1944 was promoted to the five-star rank of fleet admiral.
Admiral flote (lit.
 Admiral of the Fleet) is the fifth and highest Admiral of the Croatian Navy.
 This officer is referred to as, and is considered the equivalent of, a five-star Fleet Admiral.
 The insignia for a Croatian Senior Admiral is two thick rank stripes on both the sleeve and shoulder board.
 Between 1995 and 2002, the rank was called Stožerni admiral, meaning "Staff Admiral", analogous to "Stožerni general" for the ground forces.
The "Nimitz"-class supercarriers are a class of ten nuclear-powered aircraft carriers in service with the United States Navy.
 The lead ship of the class is named after World War II United States Pacific Fleet commander Fleet Admiral Chester W. Nimitz, the U.S. Navy's last fleet admiral.
 With an overall length of 1092 ft and full-load displacement of over 100,000 long tons, they have been the largest warships built and in service.
Ernest Joseph King (23 November 1878 – 25 June 1956) was Commander in Chief, United States Fleet (COMINCH) and Chief of Naval Operations (CNO) during World War II.
 As COMINCH-CNO, he directed the United States Navy's operations, planning, and administration and was a member of the Joint Chiefs of Staff.
 During World War II, he was the U.S. Navy's second most senior officer after Fleet Admiral William D. Leahy, who served as Chief of Staff to the Commander in Chief.
Chester William Nimitz, Sr. ( ; February 24, 1885February 20, 1966) was a fleet admiral of the United States Navy.
 He played a major role in the naval history of World War II as Commander in Chief, United States Pacific Fleet (CinCPac) and Commander in Chief, Pacific Ocean Areas (CinCPOA), commanding Allied air, land, and sea forces during World War II.
This is a complete list of four-star admirals in the United States Navy.
 The rank of admiral (or "full admiral", or "four-star admiral") is the highest rank normally achievable in the U.S. Navy.
 It ranks above vice admiral ("three-star admiral") and below fleet admiral ("five-star admiral").
Admiral (abbreviated as ADM) is a four-star commissioned naval flag officer rank in the United States Navy, the United States Coast Guard, and the United States Public Health Service Commissioned Corps, with the pay grade of O-10.
 Admiral ranks above vice admiral and below fleet admiral in the Navy; the Coast Guard and the Public Health Service do not have an established grade above admiral.
 Admiral is equivalent to the rank of general in the other uniformed services.
 The National Oceanic and Atmospheric Administration Commissioned Officer Corps has never had an officer hold the grade of admiral.
 However,  /201 § 201  of the U.S. Code established the grade for the NOAA Corps, in case a position is created that merits the four-star grade.
The National Museum of the Pacific War is located in Fredericksburg, Texas, the boyhood home of Fleet Admiral Chester W. Nimitz.
 Fleet Admiral Nimitz served as CinCPAC, Commander in Chief, United States Pacific Fleet during World War II.
 The six acre site includes the Admiral Nimitz Museum which is housed in the old Nimitz Hotel and tells the story of Fleet Admiral Nimitz beginning with his life as a young boy through his naval career as well as the evolution of the old hotel.

Question: What communications officer was on the staff of a fleet admiral in the United States Navy?
Answer: John "Jack" Roland Redman