In situtransmission electron microscopy of domain motion in thinnedBaTiO3andKNbO3shows that curved ferroelectric domains move more readily under low electric fields than do straight domain walls. We show that this relative motility arises because curved domain walls support a Maxwellian displacement charge and therefore experience a direct pressure that is proportional to the electric fieldE. Conversely, untilted charge-neutral domain walls experience a pressure proportional toE3due to induced displacement charge, and therefore tend to resist motion at low fields. Any physical process that leads to an increase in density of the immobile charge-free domain walls, relative to the more mobile curved domain walls, could lead to an increase in overall resistance to domain switching, providing an intrinsic contribution to ferroelectric fatigue. ©2000 American Institute of Physics.