Bannister often conveyed political meaning in his paintings through allegory and allusion. One of his first commissions, "The Ship Outward Bound", might have been a veiled reference to the forced return of Anthony Burns to slavery and Virginia under the Fugitive Slave Act of 1850 in 1854. In African American culture, an image of a ship leaving harbor was a clear reminder of the Transatlantic Slave Trade. Bannister's 1885 drawing "The Woodsman" is thought to be Bannister's response to the murder of Amasa Sprague, an event that spurred the abolition of capital punishment in Rhode Island after the dubious conviction and hanging of John Gordon. Similarly, his "Governor Sprague's White Horse" depicted the horse that William Sprague IV rode into the First Battle of Bull Run.