Pfc. William Johnston II, a Marine awaiting Aviation Structural Mechanic training, nears the top of the rope climb at the end of the MATSG-21 Combat Conditioning Course obstacle course. The Marines were practicing their demonstration of the course as part of the Commissioning Ceremony with Brigadier General Jon “Dog” Davis, Assistant Deputy Commandant for Aviation, on Oct. 23. - Pfc. William Johnston II, a Marine awaiting Aviation Structural Mechanic training, nears the top of the rope climb at the end of the MATSG-21 Combat Conditioning Course obstacle course. The Marines were practicing their demonstration of the course as part of the Commissioning Ceremony with Brigadier General Jon “Dog” Davis, Assistant Deputy Commandant for Aviation, on Oct. 23.