Possible Clues:

• Chess piece or British Columbia inlet
• Honour during said dark period
• He was trained in chivalry
• ... for example, Tippett's piece
• Ultimately, black on black - something black or white
• Man on board during the hours of darkness was heard
• Keep it dark that he's lost his head
• Chess piece shaped like hors's head
• Mailed long ago
• It's fair to say you sound dark, sir