Another good guide. Concise but thorough. After all, fighting the hordes is mainly a matter of following those principles you have outlined, and, most importantly, flexibility.
Might I also add something?
If you build a fort directly behind a bridge, then if the horde army defeats you, your men will fall back into it. Though one can hold off many armies on a bridge, by the time you get to the forth or fifth one, your own units are usually depleted.
If you realise you cannot hope to win the battle, do not press retreat, as your men will bypass the fort. Instead, enter battle, place your men by the red line, and withdraw immediately. They will go to the fort, thus holding the hordes off a little longer. Sometimes the hordes will even wander off again, allowing you to re-stock your army.
To prevent the fort being abandoned, put any cavalry other than Generals in to garrison it, then have them join as reinforcements. They will have plenty of time to reach the battle before they are needed.
[This message has been edited by Andalus (edited 09-03-2008 @ 12:57 PM).]