Celebrated each year on day 123, Belderone Day honors the signing of the Stenax Accords, which officially accepted that protection of the Belderone system by the Tion Hegemony, cementing Tion's promise of protection for all of Greater Tion. 

The system was re-discovered by scouts on day 116 of year 15, and the Accords were signed by Belderonian and Tionese officals in the capital of Vartholium, Belderone Prime.