I’m not going to claim I’m a medieval military tactician, but if you have some amount of resources stockpiled and friendly armies in the field, why surrender immediately? Your forces or allied forces could pin the siege force against your walls possibly giving you an advantageous position. Perhaps stockpiling supplies that didn’t go bad was difficult back then or militaries didn’t consistent of more than one army so if there was a siege that meant your main force was already defeated?
I do remember that the first phase of the Punic Wars was basically Sparta chasing all the Athenians inside the city where they brought in supplies by boat and waited the Spartans out, rinse and repeat for a decade. Obviously that’s a different period and the Athenians suffered a horrible outbreak of some sort of plague possibly due to the overcrowding.
has town walls, water on three sides, multiple independant keeps separated by curtain walls, etc. Once attackers "gained entry" they were faced with being in an enclosed space, surrounded by high archers, and tasked with as much work again to advance further ... only to be faced with the same again.
It was damn near impossible to siege as restocking from the sea and|or river was almost always an option at the time.
It was also a castle with decades of resources and cash thrown its way, other castles of the same period didn't fare nearly as well.
A great many of the Irish castles of the Ulster plantation and onwards fell to undermining - Irish sappers dug tunnels and propped the undersides of the walls .. only to later burn out all the props and collapse the walls.
There were only so many castles that had water access, multiple layered defences and granite foundations all about that resisted tunnelling.
I do remember that the first phase of the Punic Wars was basically Sparta chasing all the Athenians inside the city where they brought in supplies by boat and waited the Spartans out, rinse and repeat for a decade. Obviously that’s a different period and the Athenians suffered a horrible outbreak of some sort of plague possibly due to the overcrowding.