To cast up mounts and build forts - was the business not of the relieving but of the besieging army. Translate it: when men cast up mounts and build forts to destroy many persons.
Related Commentaries of Ezekiel 17:17
Ezekiel 17:17
17 Neither shall Pharaoh with his mighty army and great company make for him in the war, by casting up mounts, and building forts, to cut off many persons: