Joseph Finnegan (August 12, 1905 – September 8, 1980) was a

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

linguist Linguistics is the scientific study of language. The areas of linguistic analysis are syntax (rules governing the structure of sentences), semantics (meaning), Morphology (linguistics), morphology (structure of words), phonetics (speech sounds ...

and

cryptanalyst Cryptanalysis (from the Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach cryptographic se ...

with

Station Hypo Station HYPO, also known as Fleet Radio Unit Pacific (FRUPAC), was the United States Navy signals monitoring and cryptographic intelligence unit in Hawaii during World War II. It was one of two major Allied signals intelligence units, called Fl ...

during the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Early life and education

Joseph Finnegan was born and raised in

Dorchester, Massachusetts Dorchester () is a Neighborhoods in Boston, neighborhood comprising more than in the city of Boston, Massachusetts, United States. Originally, Dorchester was a separate town, founded by Puritans who emigrated in 1630 from Dorchester, Dorset, E ...

. His father was Peter Joseph Finnegan and his mother was the former Marion Catherine Connor. Joseph Finnegan had a brother and four sisters. He enlisted in the U.S. Navy in 1922 as an apprentice seaman and later served as a yeoman third class on the battleship . Finnegan attended the Naval Academy preparatory school in

San Diego, California San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

, and finished first in his class. Appointed to the

United States Naval Academy The United States Naval Academy (USNA, Navy, or Annapolis) is a United States Service academies, federal service academy in Annapolis, Maryland. It was established on 10 October 1845 during the tenure of George Bancroft as United States Secre ...

, he graduated fifteenth in a class of 153 in 1928. Finnegan served as an ensign on the battleship from August 1928 to November 1930. Promoted to lieutenant (junior grade) in 1931, he helped commission the heavy cruiser in February 1934 and then served as her radio officer.Maffeo, p. 238

Retrieved 2020-02-07. Later in 1934, Finnegan was selected by the

Office of Naval Intelligence The Office of Naval Intelligence (ONI) is the military intelligence agency of the United States Navy. Established in 1882 primarily to advance the Navy's modernization efforts, it is the oldest member of the U.S. Intelligence Community and serv ...

to attend three years of full immersion

Japanese language is the principal language of the Japonic languages, Japonic language family spoken by the Japanese people. It has around 123 million speakers, primarily in Japan, the only country where it is the national language, and within the Japanese dia ...

and culture training in

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

. While still there, he was promoted to Lieutenant in 1936. After completing his training, Finnegan was assigned to

Station CAST Station CAST was the United States Navy signals monitoring and cryptographic intelligence fleet radio unit at Cavite Navy Yard in the Philippines, until Cavite was captured by the Japanese forces in 1942, during World War II. It was an important ...

in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

in October 1937. He served there until relieved by Captain Alva Lasswell in September 1938.

War contribution

In 2002, Tex Biard described Finnegan as "intuitive" and "brilliant", and second only to Station Hypo chief Joseph J. Rochefort, saying that Finnegan's survival of the

bombing A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechan ...

of the '' USS Tennessee'' was a "fatal mistake" on the part of the

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

, and that Finnegan's survival "cost (the Japanese) the war."Transcript of Tex Biard's 2002 speech
at USSPennsylvania.org He was reattached to the Division of Naval Communications after the attack and promoted to Lieutenant Commander on January 1, 1942. Edwin T. Layton, in his book "''And I Was There: Pearl Harbor and Midway -- Breaking the Secrets''" (1985) recounts a tremendous effort by Finnegan on the Hypo team concerning the exact date on which the attack on Midway would occur. This involved the date-time groups in Japanese naval messages. Layton refers to the date-time data as being “superenciphered,” meaning that this data was preencoded even before it was added to the

JN-25 The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well. Every Japanese code was e ...

cipher. When Hypo made their all-out effort to crack this, they started by searching the stacks of printouts and

punched cards A punched card (also punch card or punched-card) is a stiff paper-based medium used to store digital information via the presence or absence of holes in predefined positions. Developed over the 18th to 20th centuries, punched cards were wide ...

for five-digit number sequences. Those they found were in low grade codes, a poor starting point, but a starting point. Layton describes this method as "involving a 12 x 31 (12 rows for months, 31 columns for day) garble check. The 31 kana apanese syllabic scriptsof the first row were A, I, U, E, O, KA, KI …………….HA, HI, HU, HE, HO. The second row was I, U, E, O ……………HE, HO, A; the third, U, E, O ……….HO, A, I, and so on, for 12 rows. At the left, representing the 12 months, was a column of 12 kana, different from those in the table – SA, AI, SU, SE, SO, TA, TI, TU, TE, TO, NA, NI (SA for January, NI for December). To encipher, for example 27 May, one picked the 5th line (May=SO), ran across to the twenty-seventh column, HA, and recorded the kana at that intersection, HO. The encipherment, then, was SO, HA, HO, the third kana providing the garble check." (Layton, pp. 427–428) Finnegan was promoted to Commander on September 15, 1942, and later promoted to Captain on March 25, 1945. He was awarded the

Legion of Merit The Legion of Merit (LOM) is a Awards and decorations of the United States military, military award of the United States Armed Forces that is given for exceptionally meritorious conduct in the performance of outstanding services and achievemen ...

for his

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

contributions.

Postwar career

Finnegan was credited with

Korean War The Korean War (25 June 1950 – 27 July 1953) was an armed conflict on the Korean Peninsula fought between North Korea (Democratic People's Republic of Korea; DPRK) and South Korea (Republic of Korea; ROK) and their allies. North Korea was s ...

service and retired from the Navy in January 1953 for medical reasons. He was buried at

Arlington National Cemetery Arlington National Cemetery is the largest cemetery in the United States National Cemetery System, one of two maintained by the United States Army. More than 400,000 people are buried in its 639 acres (259 ha) in Arlington County, Virginia. ...

on September 11, 1980.

References

{{DEFAULTSORT:Finnegan, Joseph 1905 births 1980 deaths People from Dorchester, Boston United States Navy captains United States Naval Academy alumni 20th-century American naval officers American cryptographers Intelligence analysts 20th-century cryptographers United States Navy personnel of World War II Burials at Arlington National Cemetery United States Navy personnel of the Korean War Linguists from the United States