Allen was born in Northborough, Massachusetts on September
5, 1830. He studied in Gottingen, Berlin and Rome, returning
to the States in 1856. He was a Unitarian (one who believes
in the single personality of God in contrast to the doctrine
of the Trinity). He became assistant principal at the English
and Classical School in West Newton, Massachusetts, in 1856.
During the American Civil War, he and his wife ran a school
for newly-emancipated slaves on the Sea Islands of South Carolina.
After the war, he taught at Antioch College, and in 1867,
he became a professor of ancient languages and history at
the University of Wisconsin-Madison. He died in December 1889,