Game of Thrones S3 E9, The Rains of Castamere
Robb Stark has gathered his banners and is marching on Lannister strongholds. His sisters are held captive by Cersei Lannister, but he has Jamie Lannister in his custody. His mother brokers his alliances with the Baratheon's and another wtih the Freys who hold a crucial crossing between the north and the rest of Westeros. In return Robb Stark is betrothed to one of Walder Frey's daughters. The marriage is arranged as a tactical move for Robb but a strategic one for the Freys. But the young wolf falls in love with someone else on his campaigns and marries. Walder Frey nurses the slight and Tywin Lannister finds an angle. A truce is brokered and another marriage is arranged between the Freys and the Starks, and at that celebration as the band start playing the ominous Rains of Castermere the Freys attack their guests and kill Robb, his mother and his pregnant wife. In the aftermath former bannerman of the Starks and their betrayer from within Roose Bolton is appointed warden of the North.
Edinburgh Castle, Scotland
In 1437 members of the Douglas clan assassinate King James I of Scotland, and a 7 year old James III accedes the throne. In 1439 the 5th Earl of Douglas - Archibald passes away and his 15 year old son William becomes Earl. The Black Douglases were a powerful clan in Scotland with powers of regency to rule until the king gains majority. The king's self appointed chancellor - William Crichton and his legal guardian Alexander Livingston see the Douglas clan as an existential threat to their monarch and the monarchy.
In November 1440 Crichton and Livingston orchestrate a dinner between the King, then 10, and the 16 year old Earl to get better acquainted. Guest and host were enjoying the food, entertainment and each other's company when towards the end of the meal the chancellor's men begin to pound a drum and present the guests with the ancient Scottish symbol of death - a boar's head. William Douglas and his brother David were seized from the dinner table, lead outside the Great Hall of Edinburgh Castle, found guilty at a mock trial and massacred. King James II pleaded for mercy for his guests lives but he was convinced that the Douglas brothers were plotting against the crown. The Earl is said to have asked for his brother David to be killed first so that the young boy wouldn't have to witness his brother's beheading.
The Black Dinner is part of legend and may have happened differently, but the Douglases were ended in dark circumstances. It is also speculated the Earl William's uncle James the Gross was in on the plot as he was made the 7th Earl of Douglas despite his failed attempt at laying siege to Edinburgh Castle. Twelve years later King James III invited another William, this time the 8th Earl of Douglas - to pledge allegiance. William refused and was stabbed in the throat and choked. He was then beheaded and his skull was flung out of Sterling Castle.
1. A Game of Thrones - George RR Martin
2. A Clash of Kings - George RR Martin
3. A Storm of Swords - George RR Martin