[1] His father John was descended of old Dutch stock, originally surnamed Lassing or Lassingh, who had been among the earliest settlers of the Hudson Valley.

[2] He became interested in history after reading Edward Gibbon's Decline and Fall of the Roman Empire, John Marshall's The Life of George Washington, and the Bible.

Rothchild's weekly Family Magazine from 1839 to 1841 and launched his literary career with the publication of his Outline of the History of Fine Arts.

During this time, Lossing sat for a portrait by Thomas Seir Cummings (1804–1894), now in the collection of the Metropolitan Museum of Art, New York City.

Lossing's significance as a historian derives from his diligence in seeking out primary records, his interviews with participants of events and intimates of his biographical subjects, and his care to weigh and contrast details of his various sources.

Washington Irving, with whom he corresponded, wrote, "I have been gratified at finding how scrupulously attentive you have been to accuracy to facts, which is so essential in writings of an historical nature.

"[5] This made him an essential secondary source for contemporary and succeeding historians, such as Theodore Roosevelt in his The Naval War of 1812.

There Benson had built a fireproof library to house his collection of over five thousand books and documents associated with the American Revolution and the framing of the Constitution.

Lossing was actively involved in charitable, civic, literary, and historical societies, most notably serving as a charter trustee of Vassar College in Poughkeepsie.