Relatively soon after Warhammer Fantasy Battle 3rd edition came out, a supplement called Warhammer Siege was released. It detailed some rather complex rules to handle sieges in Warhammer. (On the other hand, the 3rd edition rules were complex already, so by comparison Warhammer Siege wasn't much different)
In trying it out, while I had read the sample scenario at the back of the book and thought it was interesting, I quickly dismissed it as not epic enough. We had to try a HUGE EPIC BATTLE (classic mistake). No minor siege of an insignificant keep would this be, where we could learn the rules a little bit at a time and have a clue about what we were doing. Rather, it would be the assault upon a High Elf city by a huge Evil Army, consisting of Chaos, Orcs & Goblins, Dark Elves, you name it.
We used the "Mighty Fortress" that Citadel Miniatures had recently released, a neat styrofoam castle that has stood up to the test of time.
Here's mine, 22 years old, and still in great shape.
So we had the battle. The evil horde forms up outside the city, while the defenders stand guard on the ramparts, stoically watching their approach. The evil forces prepared for a long siege of digging sapper's trenches, tunnels to undermine the walls, and battering at the walls with their siege engines.
Turn One. The evil stone thrower threw its first stone at the city wall, aiming for the main gates. The stone impacted right on target, and the entire gate house section collapsed, completely breaching the wall.
Apparently we underestimated the power of the stone thrower--we didn't want a wussy one in this "epic" battle, so we took a huge one. And it practically vaporized the castle.
With the gatehouse breached (read: blown away), the Chaos Warrior Cavalry charged forwards, the rest of the evil army swarming to follow. Out of the breach the High Elf Cavalry charged to meet them. Very quickly, however, we determined that the forces of good had little chance to survive, as they were outnumbered by a huge margin and effectively had no defensive advantage anymore. After a few turns of horrendous carnage we called it a day.
We barely scratched the surface of the siege rules during the game, but we had fun nonetheless. The next time I did a siege I would have to be a little more reserved concerning the army size...