Seiges where the defendants were vastly outnumbered but sucessful

Jan 2018
Sturgeon Lake Mn.
I would posit that the presence of fortifications, permanent or ad hoc, would be one defining element. The other would be the complete isolation of the defended point.
Isolation yes. A siege requires the place be invested. Many confuse attacking a place with besieging it. For instance with regards to the War of the Rebellion (also known as the American Civil War) people often refer to the siege of Petersburg which was actually an intrenched confrontation, like the Western Front of the Great War. And people call the situation at Chattanooga after Chickamauga a siege but it also was just a confrontation as the Federal army in Chattanooga wasn't surrounded and had a clear line of retreat. Yeah, they were in a pickle but not besieged.
Feb 2016
1388 Seige of Dunbar.
Lady Agnes and a “handful” of retainers defy 10-20 000 English troops in a 5 month siege.

Lady Mary Bankes held Corfe Castle for 3 years, initially she had only 5 men and was besieged by 200, later she had 80 reinforcements, but the besiegers numbered 600. The castle was never taken by force, all attacks were repelled... it eventually fell to betrayal... but she was allowed to keep her keys, and was given good terms.


Ad Honorem
Dec 2014
Well, I would add the Siege of Baler, held by a 50 soldiers detachment from July 1st, 1898 to June 2nd, 1899... it means 337 days, I guess. Since they were attacked by an impossible to number but close to 10,000 rebels ... and since the possition was never taken by the enemy and since they were not made POW...
Oct 2011
Battle of Sinj, 1715.: Ottoman army of 60 000 soldiers laid siege to fort in city of Sinj, defended by 700 Croatian troops. Siege lasted from 8th to 13th August, and on 14th Turks launched an all-out assault. It was repelled, and the Ottoman army withdrew.

Siege of Guns, 1532: Ottoman army of 120 000 - 200 000 soldiers laid siege to town of Guns (Koszeg), defended by Nikola Jurišić with 700 - 800 troops. After 25 days of siege, Ottoman army withdrew at the arrival of August rains.