Sentence:  Others , badly wounded , gripped hands in manes , knees in bellies , held on as long as possible and then , weak from ghastly wounds , <WSD>slipped</WSD> sideways , slowly , almost thoughtfully , to be broken under the slashing hoofs . 
Meaning of the word marked with <WSD> tags:  move obliquely or sideways, usually in an uncontrolled manner