Possible Clues:

• Writing in French is to Richelieu very important
• Landmark ruling on this - or struggle
• Important, from the past
• Important and/or old
• 22 is, or could be, momentous
• Bosworth is to Richard somewhat as Agincourt is to English?
• Like one for the books
• Of what is important in the past
• Connecting with old times
• From long ago, famous ostrich I slaughtered