Siege of Storm's End

The Siege of Storm's End was a year-long siege during Robert's Rebellion. Following his defeat at the Battle of Ashford, Robert Baratheon fled north to Stoney Sept.

While the rebellion raged on, Lord Mace Tyrell, Warden of the South, besieged the castle for an entire year. True to his orders, Stannis resisted and refused to yield despite being forced to eat the horses, cats and dogs of the castle, and eventually even rats and glue.

Stannis and the garrison would've starved if not for the intervention of a smuggler named Davos, who managed to slip through the loyalist navy blockading Storm's End by sea and delivered a cargo of onions and salt fish. Thanks to Davos' the garrison survived long until Ned Stark arrived to lift the siege.

As reward for his service, Davos was elevated to knighthood, becoming Davos of House Seaworth given a castle and lands and a place in Stannis' household for him and his children.

In the books
In the Song of Ice and Fire novels, the story of the Siege of Storm's End is the same, with Mace Tyrell leading the land forces and Lord Paxter Redwyne leading the loyalist fleet. During the siege, a few men of Stannis' garrison planned on opening the gates to the Tyrell army, which openly feasted before the walls of Storm's End. Stannis wanted to send them to the Tyrells by catapult, but Maester Cressen convinced Stannis to keep the would-be traitors imprisoned just in case the garrison required to resort to cannibalism to survive. However the siege was lifted before such measure was neccessary.