A surgical instrument comprising: an elongate shaft assembly defining a shaft axis; a surgical end effector operably coupled to said elongate shaft assembly by an articulation joint such that said surgical end effector is selectively articulatable relative to said elongate shaft assembly about an articulation axis (B-B) that is transverse to said shaft axis; a longitudinally movable flexible firing beam configured to flexibly traverse said articulation joint and being selectively axially movable from a starting position to an ending position within said surgical end effector; a middle support member movably coupled to said elongate shaft assembly for axial and pivotal travel relative thereto and being pivotally coupled to said surgical end effector; a U-shaped proximal support link comprising a proximal top member and two proximal side members (945, 946), said U-shaped proximal support link extending over a proximal portion of said longitudinally movable flexible firing beam such that one of said proximal side members is adjacent one lateral side of said proximal portion of said longitudinally movable flexible firing beam and another one of said proximal side members is adjacent another lateral side of said proximal portion of said longitudinally movable flexible firing beam, said proximal top member movably interfacing with said middle support member; and a U-shaped distal support link comprising a distal top member and two distal side members (955, 956), said U-shaped distal support link extending over a distal portion of said longitudinally movable flexible firing beam such that one of said distal side members is adjacent one lateral side of said distal portion of said longitudinally movable flexible firing beam and another one of said distal side members is adjacent another lateral side of said distal portion of said longitudinally movable flexible firing beam, said distal top member movably interfacing with said middle support member, wherein said proximal top member movably interfaces with said elongate shaft assembly and wherein said distal top member movably interfaces with a portion of said surgical end effector. an elongate shaft assembly defining a shaft axis; a surgical end effector operably coupled to said elongate shaft assembly by an articulation joint such that said surgical end effector is selectively articulatable relative to said elongate shaft assembly about an articulation axis (B-B) that is transverse to said shaft axis; a longitudinally movable flexible firing beam configured to flexibly traverse said articulation joint and being selectively axially movable from a starting position to an ending position within said surgical end effector; a middle support member movably coupled to said elongate shaft assembly for axial and pivotal travel relative thereto and being pivotally coupled to said surgical end effector; a U-shaped proximal support link comprising a proximal top member and two proximal side members (945, 946), said U-shaped proximal support link extending over a proximal portion of said longitudinally movable flexible firing beam such that one of said proximal side members is adjacent one lateral side of said proximal portion of said longitudinally movable flexible firing beam and another one of said proximal side members is adjacent another lateral side of said proximal portion of said longitudinally movable flexible firing beam, said proximal top member movably interfacing with said middle support member; and a U-shaped distal support link comprising a distal top member and two distal side members (955, 956), said U-shaped distal support link extending over a distal portion of said longitudinally movable flexible firing beam such that one of said distal side members is adjacent one lateral side of said distal portion of said longitudinally movable flexible firing beam and another one of said distal side members is adjacent another lateral side of said distal portion of said longitudinally movable flexible firing beam, said distal top member movably interfacing with said middle support member, wherein said proximal top member movably interfaces with said elongate shaft assembly and wherein said distal top member movably interfaces with a portion of said surgical end effector.