An apparatus, the apparatus comprising: (a) a body assembly; (b) a shaft extending distally from the body assembly; (c) an end effector attached to the shaft, wherein the end effector comprises: (i) a jaw, (ii) an anvil pivotable from an open position to a closed position relative to the jaw, and (iii) a knife member configured to translate relative to the anvil in order to sever tissue; and (d) a cartridge defining a longitudinal channel, wherein the knife member is configured to translate within the longitudinal channel, wherein the cartridge comprises: (i) a deck comprising an upper surface facing toward the anvil, (ii) a buttress assembly, wherein a first portion of the buttress assembly is positioned on top of the deck, wherein a second portion of the buttress assembly is positioned within the longitudinal channel, and (iii) a folding sled configured to translate within the longitudinal channel to move the second portion of the buttress assembly to a position that is above the deck in response to actuation of the knife member, wherein the folding sled comprises a projection, wherein the knife member is configured to drive the folding sled via the projection, wherein the folding sled further comprises a folding arm to move the second portion of the buttress assembly to the position that is above the deck, characterised in that the folding arm is extending proximally relative to the projection, wherein the folding arm comprises a proximal end, wherein the knife member is configured to sever tissue distal to the proximal end of the folding arm. (a) a body assembly; (b) a shaft extending distally from the body assembly; (c) an end effector attached to the shaft, wherein the end effector comprises: (i) a jaw, (ii) an anvil pivotable from an open position to a closed position relative to the jaw, and (iii) a knife member configured to translate relative to the anvil in order to sever tissue; and (i) a jaw, (ii) an anvil pivotable from an open position to a closed position relative to the jaw, and (iii) a knife member configured to translate relative to the anvil in order to sever tissue; and (d) a cartridge defining a longitudinal channel, wherein the knife member is configured to translate within the longitudinal channel, wherein the cartridge comprises: (i) a deck comprising an upper surface facing toward the anvil, (ii) a buttress assembly, wherein a first portion of the buttress assembly is positioned on top of the deck, wherein a second portion of the buttress assembly is positioned within the longitudinal channel, and (iii) a folding sled configured to translate within the longitudinal channel to move the second portion of the buttress assembly to a position that is above the deck in response to actuation of the knife member, (i) a deck comprising an upper surface facing toward the anvil, (ii) a buttress assembly, wherein a first portion of the buttress assembly is positioned on top of the deck, wherein a second portion of the buttress assembly is positioned within the longitudinal channel, and (iii) a folding sled configured to translate within the longitudinal channel to move the second portion of the buttress assembly to a position that is above the deck in response to actuation of the knife member,