The Collaborative International Dictionary of English v.0.48:

Sledge \Sledge\, n. [AS. slecge,from sle['a]n to strike, beat.
   See Slay, v. t.]
   A large, heavy hammer, usually wielded with both hands; --
   called also sledge hammer.
   [1913 Webster]

         With his heavy sledge he can it beat.    --Spenser.
   [1913 Webster]