Yes, castle commanders will surrender if significantly outnumbered, or you prolong the seige for 30 days and they run out of food.
The Great Commander
Sudeley Castle Gloucestershire
A castle siege is when the enemy, surrounds the castle and they are going to attack and doesn't let anyone in or out or either forcing the castle residents to surrender or die from lack of food.
William Waller has written: 'Certain propositions made by Sir William Waller at the surrender of Arundell-Castle' -- subject(s): History, Arundel Castle (Arundel, England), Great Britain Civil War, 1642-1649
The governor or commander of a fortress or castle is a castellan.
abond your castle and surrender outpost's
Katsu Kaishû
"Run along the battlements of the castle" ordered the commander to the archers.
If you do not want to use men or supplies, your best strategy is threats. Surrender your castle to me, or I am going to do something terrible to you. Of course, you can't make good on that threat without using men and supplies, but then, there is some chance that you won't have to make good on the threat because the castle will just surrender, as you have ordered. Sometimes it works.
If I were you, I would try blackmail. Here's an example: Man: Hey! If you don't surrender, I'll tell the neighboring country about the thing you did with their princess" Castle Soldier: But I didn't-- Man: Oh I'm sure they will believe you...
there is 1600 rooms in the Edinburgh castle
Yes, you have to be at least level 15.