Thank you weasel_airlift, I have not heard about the coal bomb. Since the guerillas would be secretly back by Germany, this is something that the Germans could make and supply the guerillas with.
"The
coal torpedo was a hollow iron casting filled with explosives and covered in coal dust, deployed by the
Confederate Secret Service during the
American Civil War, and intended for doing harm to
Union steam transportation. When shoveled into the
firebox amongst the coal, the resulting explosion would at the very least damage the
boiler and render the engines inoperable. At worst, a catastrophic
boiler explosion would kill crewmen and passengers, start a fire, or even sink the vessel."