In 1850, John Smith Sewall graduated from Bowdoin College, Portland, Maine. To pay off college debts, he enlisted in the United States Navy. After basic training, the Navy assigned him to the USS Saratoga as a captain's clerk. Sewall wrote that sea duty meant "two years of waltzing to and fro and flitting up and down the coast" making stops in Manila, the Madjicosima Islands, Macao, Hong Kong, and Shanghai. The Saratoga joined the East Asia Squadron and followed Commodore Perry to Japan in 1853-54, as one of the infamous "Black Ships."
Several years after returning to the United States, Sewall was ordained a Congregational minister. In 1859, he was appointed pastor in Wenham, Massachusetts, where he stayed until 1867. Sewall continued to serve the U.S. military as Chaplain to the 8th Massachusetts regiment in the Civil War.
In the late 1860s, Sewall pursued a career in academia. From 1875 to 1903, he was a professor at his alma mater, Bowdoin. He finished his career at Bangor Theological Seminary as a professor of Homiletics, the art of preaching.
A half century after his return from Japan, in 1905, Sewall wrote The Logbook of the Captain's Clerk: Adventures in the China Seas, to recount his experiences during the Japan expedition. He is also the author of a half dozen books and a number of essays ranging from theology to history, some of which appeared in the Yale/New Englander Review.