A surgical stapling instrument, comprising: a shaft assembly comprising a drive shaft; an articulation joint; and an end effector assembly attached to said shaft assembly by said articulation joint such that said end effector assembly is configured to be articulated relative to said shaft assembly, wherein said end effector assembly comprises: a first jaw; a second jaw movable relative to the said first jaw; a cartridge body comprising a plurality of staple cavities; a plurality of staples removably stored in said staple cavities; an anvil configured to deform said staples, wherein said second jaw comprises said anvil; and a drive system, comprising: a main drive operably engaged with said drive shaft and configured to receive rotary motions therefrom; a closure drive configured to be selectively driven by said main drive, wherein, when driven, said closure drive is configured to move said second jaw; a firing drive configured to be selectively driven by said main drive, wherein, when driven, said firing drive is configured to fire said staples; and a shifting assembly configured to move between a first position and a second position to shift between the selective drivability of said closure drive and said firing drive, characterised in that said shifting assembly is configured to move to a third position to permit said main drive to drive both said closure drive and said firing drive simultaneously. a shaft assembly comprising a drive shaft; an articulation joint; and an end effector assembly attached to said shaft assembly by said articulation joint such that said end effector assembly is configured to be articulated relative to said shaft assembly, wherein said end effector assembly comprises: a first jaw; a second jaw movable relative to the said first jaw; a cartridge body comprising a plurality of staple cavities; a plurality of staples removably stored in said staple cavities; an anvil configured to deform said staples, wherein said second jaw comprises said anvil; and a drive system, comprising: a main drive operably engaged with said drive shaft and configured to receive rotary motions therefrom; a closure drive configured to be selectively driven by said main drive, wherein, when driven, said closure drive is configured to move said second jaw; a firing drive configured to be selectively driven by said main drive, wherein, when driven, said firing drive is configured to fire said staples; and a shifting assembly configured to move between a first position and a second position to shift between the selective drivability of said closure drive and said firing drive, characterised in that a first jaw; a second jaw movable relative to the said first jaw; a cartridge body comprising a plurality of staple cavities; a plurality of staples removably stored in said staple cavities; an anvil configured to deform said staples, wherein said second jaw comprises said anvil; and a drive system, comprising: a main drive operably engaged with said drive shaft and configured to receive rotary motions therefrom; a closure drive configured to be selectively driven by said main drive, wherein, when driven, said closure drive is configured to move said second jaw; a firing drive configured to be selectively driven by said main drive, wherein, when driven, said firing drive is configured to fire said staples; and a shifting assembly configured to move between a first position and a second position to shift between the selective drivability of said closure drive and said firing drive, characterised in that a main drive operably engaged with said drive shaft and configured to receive rotary motions therefrom; a closure drive configured to be selectively driven by said main drive, wherein, when driven, said closure drive is configured to move said second jaw; a firing drive configured to be selectively driven by said main drive, wherein, when driven, said firing drive is configured to fire said staples; and a shifting assembly configured to move between a first position and a second position to shift between the selective drivability of said closure drive and said firing drive, characterised in that said shifting assembly is configured to move to a third position to permit said main drive to drive both said closure drive and said firing drive simultaneously.