Definition of "defenceless"

The hawk, foul murderer of defenceless birds, has sighted the chicken on the bare patch.

1934, Henry G. Lamond, An Aviary On The Plains, page 95

Railway engines have been attacked with gunfire by raiding aircraft on both sides of the Channel and the impression has grown up that they are defenceless monsters to be pestered with impunity. The first engine to disprove this vainglorious theory was, we are glad to note, a British one. [The locomotive boiler exploded, causing the aircraft to crash.]

1943 March and April, “Notes and News: Southern Locomotive Destroys Raider”, in Railway Magazine, page 119