Claim on the High Kingdom (concept)
Chevalie has been united and disbanded many times in its history, often dozens of years apart, and thus the idea of claiming the High Kingdom is both common and nebulously defined. Anybody with the Claimant to the High Kingdom modifier gains a free conquest Casus Belli on any others holding a claim. The Claimant to the High Kingdom can be gained through the 'Claim Chevalie' decision, which can be taken by any independent Chevalien ruler located within Chevalie at a cost.
If the High Kingdom title is broken, then Marcher rulers can take the 'Reunite Chevalie' decision if they have the Claimant to the High Kingdom modifier to regain the High Kingdom if they completely control one of the five main kingdoms in Chevalie and either own all the titles or have ensured no other ruler does. This period will only last for thirty years, however, afterwards all claims are invalidated and Chevalie must be united manually.