.... and he's not a total idiot so he sent his troops out to the seaside or whatever at the time when your attack hit, so now the game thinks he's really weak and can't defend himself, so won't let you attack again until he's built his wall back up a level and then he'll duck you again.
So either fix PvP or loosen PvE so we can hit more than 5 times a day. Both broken makes it a non-game and good luck getting another batch of players as willing as the current lot.
We can't damage another player's city to any extent, we can't capture it and all they need to do is send their troops and res to an alt and send it back afterwards, like mad-dog does.