Sanborn was a member of the Secret Six, influential abolitionists who secretly funded John Brown's raid on Harper's Ferry. The others included Thomas Wentworth Higginson, Samuel Gridley Howe, Theodore Parker, Gerrit Smith, and George Luther Stearns. Brown had planned to captured rifles at the armory in Harper's Ferry and lead a slave rebellion in the South. Brown met with the Six several times to discuss how he'd attack the slave rebellion, but it's unclear how much they knew about his plans. Brown's raid failed, and the Secret Six were exposed during the trial that followed.
The Six scattered. Sanborn, along with Howe and Stearns, took refuge in Canada for a while. Then Sanborn returned to face the marshals in Concord.
Franklin Benjamin Sanborn was born in Hampton Falls, N.H., on Dec. 15, 1831. He was a journalist, author, reformer and troublemaker from an early age. When he was 9 he decided slavery was wrong and the U.S. Constitution should be revised or revoked. He graduated from Harvard in 1855, then became a member of the Free Soil Party in New Hampshire and Massachusetts.
He lived in Concord, Mass., among the Transcendentalists, including Ralph Waldo Emerson and Henry David Thoreau. He wrote early biographies of many of them. He later founded the American Social Science Association, 'to treat wisely the great social problems of the day.'
Sanborn defended Brown after he was hanged in 1859.
On the night of April 3, 1860, five federal marshals came to Sanborn’s home, handcuffed him and tried to put him into a coach. They intended to take him to Washington so he could answer a U.S. Senate committee’s questions about Harper’s Ferry. Sanborn resisted, expecting the townspeople to come to his aid. They did. About 150 townspeople rushed outside to prevent the marshals from taking him away.
Judge Ebenezer Hoar issued a writ demanding Sanborn’s return. The marshals let him go.
Later, Louisa May Alcott wrote in a letter:
Sanborn was nearly kidnapped. Great ferment in town. Annie Whiting immortalized herself by getting into the kidnapper's carriage so that they could not put the long legged martyr in.