The First Swynfaredian Civil War

Referred to by the Swynfaredian nobles as the "The War of the Dragon Bloods."
The first generation of Swynfaredian nobility, every single one of them were practicing sorcery by young adulthood.
Then a small percentage of the noble families' children were squibs.  Gradually the number of squib births increased.
The First Swynfaredian Civil War occurred when the eldest son of the king turned out to be a squib and his younger brother challenged him for the crown.

The Conflict

Outcome

A lot of soldiers died fighting on both sides.
The younger brother was crowned king.  His older brother was executed.  While very few of the "Squib king's" allies were put to the sword, a lot of them had land, property and titles removed from them.

Aftermath

Succession laws were re-written so that all titles would pass to the eldest direct male heir who had sorcerous talent.

Historical Significance

The Swynfaredian nobility used their magical prowess and draconic heritage as justification for their right to rule. It was implied, but never explicitly written into law that sorcerous talent was tied to the right to rule.
They formed a feudal monarchy similar to what was found in other regions though the vast majority of their nobles had sorcerous talent. The talent for sorcery gradually thinned and at one point the heir to the monarchy had no innate arcane talents at all. His younger brother challenged his right to the kingship.  Both claimants to the throne had many backers and this led to full on Civil War.

Legacy

Before the First Civil War, while outsiders could qualify for hereditary titles, the four founding houses were the only formally recognized Swynfaredian noble houses.  After the war, other houses were created to reward the victorious king's supporters. The first such house to be recognized was House Gareth.

Conflict Type

War

Battlefield Type

Land

Conflict Result

The younger challenger won, cementing the primacy of sorcerers in Swynfaredia.