The ship is described as having undergone changes to her armament to make her more formidable in the event she meets a rebel privateer. In the previous year, the U.S. Consul in Victoria, BC, believed he had discovered a plot by confederate sympathizers to seize the Shubrick and make her a rebel privateer. Fortifying the ship may have been a response to this and other plots to take command of ships in and about San Francisco by Confederate sympathizers with the goal of interrupting commerce and taking gold and silver for the confederate cause.
Brief report on the U.S. steamer Shubrick, which spent 24 hours in the port of Steilacoom to replenish supplies of wood and water. The Shubrick was carrying an Indian prisoner at the time.
[presumed] Charles Prosch
Puget Sound Herald
Steilacoom, W.T., Charles Prosch
Vol.6, No. 24, p.2, col. B
Washington Secretary of State: Historic Newspapers