But. Though, to answer to the "yet" of the next line.
is of old, &c. Read "hath been from of old [filled with men] as. pool [is full] of water".
they: i.e. the defenders.
flee away. Before their besiegers.
they: i.e. the captains.
Related Commentaries of Nahum 2:8
Nahum 2:8
8 But Nineveh is of olde like a pool of water: yet they shall flee away. Stand, stand, shall they cry; but none shall look back.