In the evening of this date, King James II resolved his differences with William Douglas, 8th Earl of Douglas, by stabbing him a couple of dozen times and throwing him out of a window. It may be understating matters to say that the two had many long-standing grudges against one another.
James had been King since the murder of his father James I in 1437, when he was only six years old. His mother, Queen Joan, had assumed the Regency for long enough to ensure James' succession, but the actual rule of the Kingdom was soon divided between two rival noble houses: the Douglases and the Livingstons, with Archibald Douglas (the King's first cousin) holding the government while James was himself held by the Livingstons at Stirling Castle for his "safety".
Although the Douglases' claims on the succession initially allowed them to dominate the government, their failure to seize the King's person meant that they were gradually pushed out by the Livingstons and their allies, who then moved to eliminate any and all "threats" from the Douglases to James's (or rather their own) power. They achieved this through such subtle and cunning plans as the so-called "Black Dinner", at which the sixteen-year-old Earl of Douglas and his brother were invited to dine with the ten-year-old James at Edinburgh Castle. During the meal, they were presented with a the head of a black bull (a symbol of death), then dragged out into the courtyard and summarily executed. (It may come as no great surprise to avid Game Of Thrones fans that this masterclass in skulduggery inspired the series' best-known bloodbath, the Red Wedding.)
Naturally, the Douglases did not take kindly to such poor hospitality, though they initially blamed their persecution on James' handlers. They therefore continued to make alliances against their enemies, and to escalate the feud between them by making violent raids against their lands and castles. Soon the nation was nearly split in two, as the lesser houses chose sides between the Douglases and the Livingstons.
Through these tactics, both sides had contrived to maintain power by making it virtually impossible for the King to rule without their consent. Therefore, even though James threw the Livingstons out of official government upon his majority (having no love for a family who had essentially abducted and imprisoned himself and his mother for much of his life), he was still dependent on both families. The Livingstons were relatively easy for James to control, but the Douglases proved dangerously independent.
In 1451, James attempted to curb the Douglases' power by raiding their lands during the absence of the 8th Earl, Walter Douglas, who was on a pilgrimage to Rome. Upon his return, the Earl fell back on the tactic of maintaining strength through alliances, and made pacts with the Earls of Ross and Crawford, both independently-minded men, who were also tied to the English nobility (particularly the powerful house of York).
James could not possibly allow such a threat to go unchallenged: feuding between the Scottish houses was one thing, but bringing the English court into the matter might imperil the Scottish throne itself. James therefore summoned Walter Douglas to Stirling Castle on this day in 1452 under guarantee of safe passage, in an attempt to achieve through diplomacy what could not be done by warfare.
Unfortunately, neither man had much of a gift for diplomacy. The King demanded that the Earl break permanently with his allies or face death for treason. The Earl repeatedly refused, denying the King's right to dictate the arrangements he chose for his family's security. After a short, blazing argument, with neither man willing to budge, James finally snapped.
Drawing a dirk from his belt, the King stabbed the Earl in the throat. He then stabbed him again, over twenty times, dragged him still living from his chambers and threw him out of a window into the garden below. He then sent his men out to finish the Earl off, which they did by hacking him to death with pole-axes. In the morning the Earl's body was buried where it lay.
James's extraordinary fit of pique sent shockwaves through the Kingdom. The Earl's death did not immediately end the threat of the Douglas family, naturally, but it did serve to send a serious message to their allies, illustrating the lengths to which the young King would go to safeguard his throne. Although the Douglases continued to feud with James, their final rebellion in 1455 was swiftly crushed by the King's forces, and the house was thereafter dissolved, their lands redistributed amongst James's allies and their wealth seized by the Crown.
Having eliminated the major threats to his power, James II went on to rule for a further 15 years, a period of relative prosperity and peace for Scotland. Despite that, it must be admitted that his reign, while energetic and ambitous, achieved very little for the nation materially. His expensive devotion to artillery (which would lead to his death in 1560, when a cannon he was standing beside exploded) was the source of much complaint amongst the nobility, and he was warned by Parliament in 1558 to curb his profiligate behaviour before he bankrupted the nation.
Ultimately, these events only go to show that there's just no talking to some people, and that while violence can solve things, it rarely does so well.