An endoscopic surgical stapling instrument, comprising: a handle comprising an actuator; a shaft extending from said handle; an end effector extending from said shaft, wherein said end effector comprises: a first jaw (6230, 6930) comprising a first cartridge attachment portion; a second jaw (6240, 6940) comprising a second cartridge attachment portion, wherein one of said first jaw (6230, 6930) and said second jaw (6240, 6940) is movable relative to the other of said first jaw (6230, 6930) and said second jaw (6240, 6940); a first cartridge (6200, 6900) insertable into said first jaw (6230, 6930), wherein said first cartridge (6200, 6900) is attachable to said first cartridge attachment portion, and wherein said first cartridge (6200, 6900) includes a plurality of staples, each staple comprising a base with legs extending from the base; and a second cartridge insertable into said second jaw (6240, 6940), wherein said second cartridge is attachable to said second cartridge attachment portion, wherein said second cartridge includes a retention fastener comprising a plurality of retention apertures configured to engage respective staple legs, whereby said retention fastener is configured to connect said staple legs of said plurality of staples and characterised in that said retention fastener is configured to retain said staples in stapled tissue with the staple legs unbent. a handle comprising an actuator; a shaft extending from said handle; an end effector extending from said shaft, wherein said end effector comprises: a first jaw (6230, 6930) comprising a first cartridge attachment portion; a second jaw (6240, 6940) comprising a second cartridge attachment portion, wherein one of said first jaw (6230, 6930) and said second jaw (6240, 6940) is movable relative to the other of said first jaw (6230, 6930) and said second jaw (6240, 6940); a first cartridge (6200, 6900) insertable into said first jaw (6230, 6930), wherein said first cartridge (6200, 6900) is attachable to said first cartridge attachment portion, and wherein said first cartridge (6200, 6900) includes a plurality of staples, each staple comprising a base with legs extending from the base; and a second cartridge insertable into said second jaw (6240, 6940), wherein said second cartridge is attachable to said second cartridge attachment portion, wherein said second cartridge includes a retention fastener comprising a plurality of retention apertures configured to engage respective staple legs, whereby said retention fastener is configured to connect said staple legs of said plurality of staples and characterised in that said retention fastener is configured to retain said staples in stapled tissue with the staple legs unbent. a first jaw (6230, 6930) comprising a first cartridge attachment portion; a second jaw (6240, 6940) comprising a second cartridge attachment portion, wherein one of said first jaw (6230, 6930) and said second jaw (6240, 6940) is movable relative to the other of said first jaw (6230, 6930) and said second jaw (6240, 6940); a first cartridge (6200, 6900) insertable into said first jaw (6230, 6930), wherein said first cartridge (6200, 6900) is attachable to said first cartridge attachment portion, and wherein said first cartridge (6200, 6900) includes a plurality of staples, each staple comprising a base with legs extending from the base; and a second cartridge insertable into said second jaw (6240, 6940), wherein said second cartridge is attachable to said second cartridge attachment portion, wherein said second cartridge includes a retention fastener comprising a plurality of retention apertures configured to engage respective staple legs, whereby said retention fastener is configured to connect said staple legs of said plurality of staples and characterised in that said retention fastener is configured to retain said staples in stapled tissue with the staple legs unbent.