Harriet Martineau writes about slavery

Harriet Martineau writes to Senator Wilson concerning slavery, and adds: 

Regarding  the proposal to make soldiers of the slaves, our secesh partizans don’t know what to make of it.  We of the Northern side are trying to teach them; but probably the negroes themselves will be the first  to make all clear to their heaven-born friends.  I do hope that will be attempted.  If not, the mere proposal is a great gain.

                         (Liberator,  Jan 13, 1865, pg 4)