A surgical instrument comprising: a tool drive portion configured for operable attachment to a portion of a robotic system for receiving control motions therefrom; an elongated shaft coupled to said tool drive portion ; an axially movable control member operably supported within said elongated shaft and being axially movable in response to actuation motions applied thereto from said robotic system ; and a disposable loading unit comprising: a housing coupled to said elongated shaft ; a cartridge assembly including a staple cartridge supported by said housing ; an axial drive assembly supported for selective axial travel through said cartridge assembly from a start position to an end position upon application of a rotary motion thereto; a motor supported within said housing and operably interfacing with said axial drive assembly to selectively apply said rotary motion thereto; and a power source axially movable within said housing from a disconnected position wherein said power source is disconnected from said motor to a first connected position wherein said power source provides power to said motor upon attachment to the control member , characterized in that : the surgical instrument further comprises a drive shaft assembly coupled to a proximal end of the axially movable control member , a rotary drive gear , a rotatable body portion coupled to the rotary drive gear , and a gear train in meshing engagement with the rotary drive gear and drive shaft assembly , such that rotation of the rotary drive gear results in the axial advancement of the axially movable control member . a tool drive portion configured for operable attachment to a portion of a robotic system for receiving control motions therefrom; an elongated shaft coupled to said tool drive portion ; an axially movable control member operably supported within said elongated shaft and being axially movable in response to actuation motions applied thereto from said robotic system ; and a disposable loading unit comprising: a housing coupled to said elongated shaft ; a cartridge assembly including a staple cartridge supported by said housing ; an axial drive assembly supported for selective axial travel through said cartridge assembly from a start position to an end position upon application of a rotary motion thereto; a motor supported within said housing and operably interfacing with said axial drive assembly to selectively apply said rotary motion thereto; and a power source axially movable within said housing from a disconnected position wherein said power source is disconnected from said motor to a first connected position wherein said power source provides power to said motor upon attachment to the control member , a housing coupled to said elongated shaft ; a cartridge assembly including a staple cartridge supported by said housing ; an axial drive assembly supported for selective axial travel through said cartridge assembly from a start position to an end position upon application of a rotary motion thereto; a motor supported within said housing and operably interfacing with said axial drive assembly to selectively apply said rotary motion thereto; and a power source axially movable within said housing from a disconnected position wherein said power source is disconnected from said motor to a first connected position wherein said power source provides power to said motor upon attachment to the control member , characterized in that : the surgical instrument further comprises a drive shaft assembly coupled to a proximal end of the axially movable control member , a rotary drive gear , a rotatable body portion coupled to the rotary drive gear , and a gear train in meshing engagement with the rotary drive gear and drive shaft assembly , such that rotation of the rotary drive gear results in the axial advancement of the axially movable control member . <EOS>