First Trial by Combat of Tyrion Lannister

"Lord Tyrion, you are accused of hiring a man to slay my son Bran in his bed, and of conspiring to murder my sister's husband, Lord Jon Arryn, the Hand of the King"

- Lady Catelyn Stark

The First Trial of Tyrion Lannister is an event which helps trigger the War of the Five Kings. Tyrion is taken prisoner by Lady Catelyn Stark and her sister Lysa Arryn, who accuse him of the attempted murder of Bran Stark and the murder of Jon Arryn. Tyrion ultimately demands it be settled in a trial by combat.

Background
En route back to King's Landing following from a visit to The Wall and Winterfell, Tyrion and Yoren stop at the Crossroads Inn in the Riverlands. Catelyn Stark and Ser Rodrik Cassel are also there. When Catelyn spots Tyrion she accuses him of trying to kill her son Bran by pushing him out of a window and then by hiring an assassin to do it. Catelyn had earlier been told by Petyr Baelish that the dagger found on the assassin had once belonged to him, but he had lost it in a bet to Tyrion. Tyrion is stunned by the charge and denies it. Catelyn invokes the name of her father, Hoster Tully, who rules the Riverlands, meaning the Knights in the inn owe him fealty, and Tyrion is apprehended.

Trial
To Tyrion's surprise, Catelyn does not take him back to Winterfell, but to The Eyrie in The Vale of Arryn, home of her sister Lysa. Lysa, hysterical and grief-stricken at the recent death of her husband, accuses Tyrion of murdering him too, and he is thrown into one of the Eyrie's sky cell dungeons. With the offer of a large bribe, Tyrion convinces his guard Mord to pass a message to Lady Arryn that he is ready to confess his crimes. Instead, to the amusement of those in attendance, he confesses to an array of trivial "crimes", which include stealing a servant girl's clothes, filling his uncle's boots with goat faeces and spoiling some turtle soup. Lysa orders him returned to the sky cells, but Tyrion then demands a trial by combat.

Trial by Combat
Lady Lysa reluctantly agrees to his request, but reminds Tyrion of the consequences should he lose: he will "fly" through the Eyrie's moon door. A number of Knights volunteer to be her champion, and Ser Vardis Egen is chosen. As his own champion, Tyrion names his brother, Ser Jaime Lannister, but Lysa denies his request, as Jaime is not present and she wants the trial completed quickly. It appears that no one will volunteer to fight for Tyrion, until a sellsword, Bronn, whom Tyrion had earlier met in the Crossroads Inn, steps forward and offers his services.

The combat begins, and Bronn uses underhand tactics and his greater manoeuvrability (he declines to have armor or a shield) to wear down Ser Vardis. Bronn finally stabs Vardis through the neck and pushes him out of the moon door to his death. Thus acquitted, Tyrion reclaims his purse and tosses it to Mord with the quip "a Lannister always pays his debts". He and Bronn leave the Eyrie together.

Aftermath
In response to Tyrion's abduction, his father Tywin Lannister invades the Riverlands with an army of 60,000 men and his bannerman Gregor Clegane begins attacking houses loyal to House Tully. After gathering his own army following his father Eddard Stark's execution for treason by King Joffrey, Robb Stark invades the Riverlands in support of his Tully allies, effectively triggering the War of the Five Kings.