Both Uses

cleave
in
All Quiet on the Western Front
(Edited)

The sharpened spade is a more handy and many-sided weapon; not only can it be used for jabbing a man under the chin, but it is much better for striking with because of its greater weight; and if one hits between the neck and shoulder it easily cleaves as far down as the chest.
p. 104.3

cleaves = splits or cuts through
—a blow from a spade cleaves through his face.
p. 116.4 *

Definitions:

(1) (cleave as in: cleave through)
to split or cut through something

Ironically, this word can mean to split in two or to hold together.

Note that you may see cleaved, cleft, clove, or cloven as the past tense of this sense of cleave.
(2) (cleave as in: cleave to)
to hold firmly to something -- such as an object, a person or idea

Ironically, this word can mean to split in two or to hold together.

Note that you may see cleaved, clove, or clave as the past tense of this sense of cleave.
(3) (meaning too rare to warrant focus)
a proper noun or other word too rare to warrant focus