I've only just noticed that it is no longer possible to sap the enemy walls during sieges as it was in RTW. Anyone know why it was removed? I hardly ever used it in RTW due to the plentiful heavy infantry for almost every faction but in my current Polish campaign it is occuring to me that it would be a very useful ability, to let me take a city with an all-cav army and one unit of cheap mercenary infantry (without autoresolving).

Also, why do my guys bother to build a shelter around the rams if they're not going to use it? Would be better not to bother and have the rams able to run.