Sentence:  It was pitiful to see the thin ranks of warriors , old and young , wheeling and <WSD>twisting</WSD> their ponies frantically from side to side only to be tumbled bleeding from their saddles by the relentless slam , slam of the cruelly efficient Hawkinses . 
Meaning of the word marked with <WSD> tags:  to move in a twisting or contorted motion, (especially when struggling)