obsidional

a. [ L. obsidionalis, from obsidio a siege, obsidere to besiege: cf. F. obsidional. See Obsess. ] Of or pertaining to a siege. [ 1913 Webster ]

Obsidional crown (Rom. Antiq.), a crown bestowed upon a general who raised the siege of a beleaguered place, or upon one who held out against a siege. [ 1913 Webster ]