Born in New York, the son of noted military historian, R. Ernest Dupuy, Trevor very much followed in his father's footsteps. Trevor Dupuy attended West Point, graduating in the class of 1938. During World War II he commanded a U.S. Army artillery battalion, a Chinese artillery group, and an artillery detachment from the British 36th Infantry Division. He was always proud of the fact that he had more combat time in Burma than any other American, and received decorations for service or valor from the U.S., British, and Chinese governments. After the war Dupuy served in the United States Department of Defense Operations Division from 1945 to 1947, and as military assistant to the Under Secretary of the Army from 1947 to 1948. He was a member of the original Supreme Headquarters Allied Powers Europe (SHAPE) staff in Paris under Generals Dwight D. Eisenhower and Matthew Ridgway from 1950 to 1952.

It is as a military historian and a theorist that Trevor Dupuy would make a lasting mark on the world. He is perhaps best known for his massive book The Encyclopedia Of Military History (co-written, like many of his books, with his father R. Ernest Dupuy). Starting from the beginning of history and going up the present day the book tries to cover all the major (and minor) military conflicts in world history. Usually each entry (arranged chronologically and by region) gives little more than the names of the commanders and (often) very rough estimates for the size of the forces involved in the campaigns. Dupuy was not afraid of expressing an opinion and he classified some of his subjects as Great Captains (such as Alexander the Great, Hanibal, Julius Caesar, Gustavus Adolphus of Sweden and Napoleon). Like most Western reference works it spends far more time dealing with wars in Europe and the United States than the rest of the world, but it does at least try to cover the entire world. The Encyclopedia Of Military History has been revised (and updated) several times, most recently in 1993. It can be found in the reference section of most American libraries.

After Dupuy left active service in the Army in 1952, Harvard University appointed him as a Professor of Military Science and Tactics, where he helped found the Harvard Defense Studies Program (directed from 1958 to 1971 by Henry Kissinger Henry Kissinger - Biography). He left Harvard in 1956 to become director of the program in military studies at The Ohio State University. After retiring from active military duty in 1958, he served as a visiting professor in the International Relations Program at Rangoon University (now Yangon University) in Burma. From 1960 to 1962 Dupuy worked for the Institute for Defense Analyses, a government-funded think tank.

In 1962 he formed the first of his research companies dedicated to the study and analysis of armed conflict, the Historical Evaluation and Research Organization (HERO), and served as President and Executive Director until 1983. From 1967 to 1983 he was also President of T. N. Dupuy Associates Inc. (TNDA), which became the parent organization for HERO. In 1983, TNDA sold its assets (including HERO) to a new corporation he formed called Data Memory Systems, Inc. (DMSI). Trevor was the president and largest stockholder in DMSI. In 1990, Dupuy resigned from DMSI, sold his stock and reactivated TNDA. In 1992 TNDA was closed out, and he established the non-profit The Dupuy Institute (TDI).

Dupuy committed suicide by gunshot at his home in Vienna, Virginia on June 5, 1995. He had learned three weeks earlier that he had terminal pancreatic cancer. He was buried in Arlington National Cemetery. During his lifetime he wrote or co-wrote more than 50 books.

• "My personal feeling is that if I have done anything worthwhile, it is in military theory and the relationship of the elements of historical experience to theory."

• “I was brought up by my father to be both a soldier and a military historian. To him the two were inseparable, and that is the way it has always been for me.”

• To the Colors: The Way of Life of an Army Officer (with R.E. Dupuy), Chicago, 1942
• Faithful and True: History of the 5th Field Artillery, Schwabisch-Hall, Germany, 1949
• Campaigns of the French Revolution and of Napoleon, Cambridge, Ma, 1956

• Brave Men and Great Captains (With R. E. Dupuy), New York, 1960, 1984, 1993
• Compact History of the Civil War (with R.E. Dupuy), New York, 1960, 1991
• Civil War Land Battles, New York, 1960
• Civil War Naval Actions, New York, 1961

• Military History Of World War II, New York, 1962-65 (in 18 fairly short books):

Vol. 1 - European Land Battles: 1939—1943 Vol. 2 - European Land Battles: 1944—1945

Vol. 3 - Land Battles: North Africa, Sicily, And Italy  Vol. 4 - The Naval War In The West: The Raiders

Vol. 5 - The Naval War In The West: The Wolf Packs  Vol. 6 - The Air War In The West: September 1939-May 1941

Vol. 7 - The Air War In The West: June 1941-April 1945  Vol. 8 - Asiatic Land Battles: Expansion Of Japan In Asia
Vol. 9 - Asiatic Land Battles: Japanese Ambitions In The Pacific   Vol. 10 - Asiatic Land Battles: Allied Victories In China And Burma

Vol. 11 - The Naval War In The Pacific: Rising Sun Of Nippon  Vol. 12 - The Naval War In The Pacific: On To Tokyo
Vol. 13 - The Air War In The Pacific: Air Power Leads The Way  Vol. 14 - The Air War In The Pacific: Victory In The Air

Vol. 15 - European Resistance Movements  Vol. 16 - Asian And Axis Resistance Movements

Vol. 17 - Leaders Of World War II  Vol. 18 - Chronological Survey Of World War II

• Compact History of the Revolutionary War (With R. E. Dupuy), New York, 1963
• Holidays, Editor, Contributor., New York, 1965
• Military Heritage Of America (With R. E. Dupuy, Paul Braim), 2 Vols., New York, 1966, 1986, 1992

• Military History Of World War I, New York, 1967 (in 12 fairly short books):

Vol. 1 - 1914: The Battles In The West  Vol. 2 - 1914: The Battles In The East

Vol. 3 - Stalemate In The Trenches, November 1914-March 1918    Vol. 4 - Triumphs And Tragedies In The East: 1915-17

Vol. 5 - The Campaigns On The Turkish Fronts  Vol. 6 - Campaigns In Southern Europe

Vol. 7 - 1918: The German Offensives  Vol. 8 - 1918: Decision In The West

Vol. 9 - Naval And Overseas War: 1914-15  Vol. 10 - Naval And Overseas War: 1916- 18

Vol. 11 - The War In The Air  Vol. 12 - Summary Of World War I

• The Battle Of Austerlitz, New York, 1968
• Modern Libraries For Modern Colleges: Research Strategies For Design And Development, Washington, D.C., 1968
• Ferment In College Libraries: The Impact Of Information Technology, Washington, D.C., 1968
• Mediapower: A College Plans For An Integrated Media Service System, Washington, D.C., 1968
• Military History Of The Chinese Civil War, New York, 1969

• The Military Lives Series (published in 1969 and 1970) :

The Military Life Of Alexander The Great  The Military Life Of Hannibal

The Military Life Of Julius Caesar   The Military Life Of Genghis Khan

The Military Life Of Gustavus Adolphus  The Military Life Of Frederick The Great

The Military Life Of George Washington    The Military Life Of Napoleon

The Military Life Of Abraham Lincoln  The Military Life Of Hindenburg And Ludendorff

The Military Life Of Adolph Hitler  The Military Life Of Winston Churchill

• Revolutionary War Naval Battles (With Grace P. Hayes), New York, 1970
• Revolutionary War Land Battles (With Gay M. Hammerman), New York, 1970
• Mongolia, Foreign Area Studies Handbook, Washington, D.C., 1970
• Almanac Of World Military Power 1970 (With John A. Andrews, Grace P. Hayes), New York, 1970
• Almanac Of World Military Power 1972 (With John A. Andrews, Grace P. Hayes), New York, 1972
• Documentary History Of Arms Control And Disarmament (With Gay M. Hammerman), New York, 1974
• World Military Leaders (With Grace P. Hayes, Paul Martell), 1974
• Almanac Of World Military Power 1974 (With John A. Andrews, Grace P. Hayes), New York, 1974
• People And Events Of The American Revolution (With Gay M. Hammerman), New York, 1974
• An Outline History Of The American Revolution (With R.E. Dupuy), New York, 1975
• Encyclopedia Of Military History (With R.E. Dupuy), New York, 1975, 1986, 1993
• A Genius For War: The German Army And General Staff, 1807—1945, New Jersey, 1977, 1984, 1989, 1993
• Numbers, Predictions and War, New York, 1978, 1985
• Elusive Victory: The Arab-Israeli Wars, 1947—1974, New York, 1978, 1984, 1989, 1992

• Almanac Of World Military Power 1980 (With John A. Andrews, Grace P. Hayes), New York, 1980
• The Evolution Of Weapons And Warfare, New York, 1980, 1984, 1986
• Great Battles Of The Eastern Front (With Paul Martell), New York, 1982
• Options Of Command, New York, 1984
• Flawed Victory: The Arab-Israeli Conflict And The 1982 War In Lebanon (With Paul Martell), Virginia, 1986
• Understanding War: Military History And The Theory Of Combat, New York, 1986
• Dictionary Of Military Terms (With Curt Johnson, Grace P. Hayes), New York, 1987

• Understanding Defeat, New York, 1990
• Attrition: Forecasting Battle Casualties And Equipment Losses In Modern War, Virginia, 1990
• If War Comes, How To Defeat Saddam Hussein, Virginia, 1991
• Future Wars: The World'S Most Dangerous Flashpoints, New York, 1992
• Encyclopedia Of Military Biography (With Curt Johnson, David L. Bongard), New York, 1992
• International Military And Defense Encyclopedia, (Brassey'S) 6 Vols., Editor In Chief, New York, 1992
• Hitler's Last Gamble (With David L. Bongard, Richard C. Anderson), New York, 1994
• Unpublished Manuscripts By Trevor N. Dupuy
• Great Captains And Modern War
• Military Myths (Unfinished)
• Documentary History Of The U.S. Armed Forces (Unfinished)