1625,
anslaight, somehow from or on analogy of Du.
aanslag "attack," from M.Du.
aenslach, from
aen "on" +
slach "blow," related to
slaen "slay." Spelling infl. by obs. (since c.1400) Eng.
slaught (n.) "slaughter," from O.E.
sleaht (see
slaughter). No record of its use in 18c.; apparently revived by Scott.