This was the 6th Grand Tribunal in 865 AD.
Indeed. For this in ArM5, best look up GotF p.140, with atlas-games.com/arm5/arm5errata.php#AG0276 for that page.
But Argentarium has found out already (see Domus Parva 790 A.D. - alternate setting ), that the state of the Order at the 6th Grand Tribunal - as decribed in 865 AD: Voventes Centennales in Sub Rosa 16 - is quite different from what he desires for his Domus Parva.
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