By the late 13th and early 14th century, however, sieges became much shorter due to those very same counter-weight trebuchets and other advanced siege engines. It wasn't unusual for fortified towns and castles to surrender within just a few days if no outside help arrived to break the siege. In some instances, towns surrendered at the mere mention of siege engines.

This was because the newer siege engines made sieges much more destructive. Edward I used his massive siege engines to great effect in Scotland. The aptly named Warwolf trebuchet brought several Scottish castles to surrender which were previously considered impregnable, such as Caerlaverock and Urquhart and Stirling. Even though the basic design was invented by the Chinese 1000 years earlier, the trebuchet came into its own in the high middle ages. Just a few 200-300 lb. stones hurled into your walls from beyond archer range was enough to bring most castles and fortified towns to surrender. The big limiting factor, of course, was having the skilled engineers to build it and a supply of local wood sufficient for the task. Castles and fortified towns in areas without a large supply of timber, like deserts, were much safer... until the advent of cannon, anyway.