Xalnan High Crown (a.k.a. the Broken Crown)
They made a vow to share the crown, but instead they broke both the vow and the crown.
The Xalnan High Crown was worn by the Xalnan emperor for many generations, but as a great plague swept through Xalna the emperor, Ashur II, was infected as well.
On his deathbed he made a decision that is seen by many as one of the worst in known history. He did not declare an hair, instead he asked his two sons to share power.
While they agreed to do so, neither did. The imperial court split into factions within hours after Ashur II died, one for each son.
Each faction wanted their hands on the crown, since it represented the power to rule. The first physical conflict was all about the crown. It was during this the crown was damaged.
One of the servants loyal to Ashur II managed to get their hands on the crown and instead of siding with one of the fractions, they decided to remove the crown from the court and fled to Venira asking for help to bring order back.
The Veniran government tried to open talks, but when the fractured Xalnans heard where the crown had been taken talks broke down and the War of Misunderstanding began.