A surgical stapling apparatus including: a housing; a handle supported by the housing; an elongated body extending distally from the housing; a tool assembly at the distal end of the elongated body comprising a cartridge assembly including a cartridge having a plurality of surgical fasteners therein and an anvil assembly including an anvil plate, wherein at least one of the cartridge assembly and anvil assembly is movable in relation to the other of the cartridge assembly and anvil assembly and wherein each of the anvil plate and the staple cartridge defines an elongate longitudinal slot (82b, 70b); a surgical buttress releasably secured to a tissue contacting surface of at least one of the anvil plate and the staple cartridge, wherein each surgical buttress is secured to the at least one of the anvil assembly and the cartridge assembly by at least one anchor; a release assembly associated with the at least one of the anvil assembly and the cartridge assembly; and a drive assembly slidably translatable through the tool assembly from a proximal position to a distal position, wherein the drive assembly actuates the release assembly to thereby release the anchor and to free the surgical buttress from the at least one of the anvil assembly and cartridge assembly, wherein the release assembly grips the at least one anchor prior to an actuation of the drive assembly, characterised in that at least one of the anvil assembly and the cartridge assembly, includes a constricting, open-ended, side slot configured to grip an end of the anchor ('S1', 'S2', 'S3', 'S4'), and wherein the release assembly pushes the end of the anchor out of the side slot, upon a distal advancement of the drive assembly. a housing; a handle supported by the housing; an elongated body extending distally from the housing; a tool assembly at the distal end of the elongated body comprising a cartridge assembly including a cartridge having a plurality of surgical fasteners therein and an anvil assembly including an anvil plate, wherein at least one of the cartridge assembly and anvil assembly is movable in relation to the other of the cartridge assembly and anvil assembly and wherein each of the anvil plate and the staple cartridge defines an elongate longitudinal slot (82b, 70b); a surgical buttress releasably secured to a tissue contacting surface of at least one of the anvil plate and the staple cartridge, wherein each surgical buttress is secured to the at least one of the anvil assembly and the cartridge assembly by at least one anchor; a release assembly associated with the at least one of the anvil assembly and the cartridge assembly; and a drive assembly slidably translatable through the tool assembly from a proximal position to a distal position, wherein the drive assembly actuates the release assembly to thereby release the anchor and to free the surgical buttress from the at least one of the anvil assembly and cartridge assembly, wherein the release assembly grips the at least one anchor prior to an actuation of the drive assembly, characterised in that at least one of the anvil assembly and the cartridge assembly, includes a constricting, open-ended, side slot configured to grip an end of the anchor ('S1', 'S2', 'S3', 'S4'), and wherein the release assembly pushes the end of the anchor out of the side slot, upon a distal advancement of the drive assembly.