Perhaps Sparks's most well-known work today is his biographies of George Washington. To complete the work, he sought out original documents, including letters and whatever first-hand testimony he could find. First published as a multi-volume Life and Letters of George Washington beginning in 1834, a simplified and abridged version was published as Life of George Washington in 1842. He also wrote books or articles on a variety of other figures associated with the American Revolution, including Benjamin Franklin, John Andre, Benedict Arnold, Charles Lee, and Anthony Wayne.
Sparks chose to focus on the origins of the country because of what he considered a contentious contemporary period in American politics. Looking to the past, he said, was "the polestar to which all may look for safety." Perhaps so, but Sparks also took liberties in writing about the Revolution and its major figures by creating an illusion of perfect harmony. One contemporary wrote that Sparks was guilty of "flagrant literary misdemeanour" by re-wording much of the correspondence he used as a source for his own writing. After his death, one critic noted that Sparks had "altered" and "embellished" Washington's letters to ensure that the historical figure matched the presumed dignity and character that fit Sparks's purpose of harmony. Consider this excerpt titled "American History":
Besides a love of adventure, and an enthusiasm that surrounded every difficulty, the character of its founders was marked by a hardy enterprise and sturdiness of purpose, which carried them onward through perils and sufferings, that would have appalled weaker minds and less resolute hearts. This is the first great feature of resemblance in all the early settlers, whether they came to the north or to the south, and it merits notice from the influence it could not fail to exercise on their future acts and character, both domestic and politic. The timid, the wavering, the feeble-minded, the sons of indolence and ease, were not among those who left the comforts of home, braved the tempests of the ocean, and sought danger on the shores of an unknown and inhospitable world.
Enduring his final illness, Sparks was surrounded by family and friends. His friends insisted his final days were "painless and placid". His children recorded among his last words, "Strive to do good and you will bring it to pass." His substantial collection of manuscripts and books were