*** the stakes that the sappers had pushed into the earth behind the long grass , and the concealed holes they 'd dug to catch and break the horses ' legs , had done their work ; the first rash impetus of the enemy 's onrush had been broken , and those who had n't fallen were isolated , a mere handful of riders whose speed had carried them out into the empty plain , while those backed up behind were confused , circling aimlessly like fallen trees in the rapids of a flooding river .