Nathaniel Hawthorne published his first novel, Fanshawe (1828) anonymously and at his own expense. He was so embarrassed by its poor critical reception that he actually burned all of the unsold copies (source).
While Hawthorne was at college at Bowdoin, he became good friends with the future fourteenth president of the United States, Franklin Pierce. Hawthorne wrote campaign materials for Pierce, and after Pierce won, he gave Hawthorne one of the plummest jobs in the whole presidential arsenal: ambassador to England. (This was in the late 1850s, after the publication of The House of the Seven Gables.) (source)
Hawthorne, who died in 1864, lived to see the beginning of the Civil War. In 1862 he published an editorial in the Atlantic Monthly called "Chiefly About War Matters By a Peaceable Man". In it, he wrote a physical description of Abraham Lincoln's ugliness that was considered so politically sensitive that it wound up getting censored until long after the war's end and the deaths of both men.
Hawthorne was best friends with another pioneer of American literature, Herman Melville. While we don't have any of Hawthorne's letters to Melville, some of Melville's friendly, enthusiastic letters to Hawthorne have survived. (Read them here!) Melville actually dedicated his greatest work, Moby-Dick, to the "genius of Nathaniel Hawthorne."
In a review of Hawthorne's collection Twice-Told Tales, Edgar Allan Poe used Hawthorne's example to define the American short story for the first time (source).