He graduated from City College of New York, Yeshiva University, and Columbia University.He taught in the public schools New York City.He is Chairman of the history department at Yeshiva University.

He lives with his wife in the Bronx, New York.

• The Church of England in the first world war, Columbia University., 1968
• Sir Norman Angell, Twayne Publishers, 1979, ISBN 9780805777253

• The airman's war: World War II in the sky, Atheneum, 1982, ISBN 9780689309076
• Overlord: D-Day and the invasion of Europe, Atheneum, 1982, ISBN 9780689309311
• Victory in the Pacific, Atheneum, 1983
• The sea rovers: pirates, privateers, and buccaneers, Atheneum, 1984, ISBN 9780689310294
• War clouds in the West: Indians & cavalrymen, 1860-1890, Atheneum, 1984, ISBN 9780689310669
• The secret armies: spies, counterspies, and saboteurs in World War II, Atheneum, 1985, ISBN 9780689311659
• 1812, the war nobody won, Atheneum, 1985, ISBN 9780689310751
• Aztecs and Spaniards: Cortés and the conquest of Mexico, Atheneum, 1986, ISBN 9780689311765
• The Yanks are coming: the United States in the first World War, Atheneum, 1986, ISBN 9780689312090
• Hitler, Viking Kestrel, 1987, ISBN 9780670815463
• Struggle for a Continent: The French and Indian Wars, 1690-1760, Atheneum, 1987, ISBN 9780689313134
• The war for independence: the story of the American Revolution, Atheneum, 1988, ISBN 9780689313905
• Inca & Spaniard: Pizarro and the conquest of Peru, Atheneum, 1989, ISBN 9780689314810
• Mao Tse-tung and his China, Viking Kestrel, 1989, ISBN 9780670829408
• The Spanish-American War, Atheneum, 1991, ISBN 9780689316630
• America and Vietnam: the elephant and the tiger, Viking, 1992, ISBN 9780670840632
• Stalin Puffin Books, 1993, ISBN 9780140326055
• Napoleon and the Napoleonic Wars, Puffin Books, 1993, ISBN 9780140364798
• Cowboys, Indians, and gunfighters: the story of the cattle kingdom, Atheneum, 1993, ISBN 9780689317743
• Virginia's general: Robert E. Lee and the Civil War, Atheneum, 1994, ISBN 9780689318382
• Unconditional surrender: U.S. Grant and the Civil War, Atheneum, 1994, ISBN 9780689318375
• The sea king: Sir Francis Drake and his times, Atheneum Books for Young Readers, 1995, ISBN 9780689318870
• Plains warrior: Chief Quanah Parker and the Comanches, Atheneum Books for Young Readers, 1996, ISBN 9780689800818
• Commander in Chief Abraham Lincoln and the Civil War, Dutton Children's Books, 1997, ISBN 9780525458227
• Empires lost and won: the Spanish heritage in the Southwest, Atheneum Books for Young Readers, 1997, ISBN 9780689804144
• Terror of the Spanish Main: Sir Henry Morgan and his buccaneers, Dutton Children's Books, 1999, ISBN 9780525459422
• Sitting Bull and his world, Dutton Children's Books, 2000, ISBN 9780525459446
• George Washington and the founding of a nation, Dutton Children's Books, 2001, ISBN 9780525464815
• Dr. Jenner and the speckled monster: the search for the smallpox vaccine, Dutton Children's Books, 2002, ISBN 9780525469223
• Secrets from the rocks: dinosaur hunting with Roy Chapman Andrews, Illustrator Albert Marrin, Dutton Children's Books, 2002, ISBN 9780525467434
• Old Hickory: Andrew Jackson and the American People, Dutton Children's Books, 2004, ISBN 9780525472933
• Oh, rats!: the story of rats and people, Illustrator C. B. Mordan, Dutton Children's Books, 2006, ISBN 9780525477624
• Saving the buffalo, Scholastic Nonfiction, 2006, ISBN 9780439718547
• The great adventure: Theodore Roosevelt and the rise of modern America, Dutton Children's Books, 2008, ISBN 9780525476597