Duchy
A duchy is the domain of a Duke or Duchess. Within the Star Kingdom of Manticore[1], a duchy is also an administrative district.
Use in TRMN
Within The Royal Manticoran Navy: The Official Honor Harrington Fan Association, Inc. a duchy is the fictitious territory, or "peerage land" bestowed on an duke or duchess. This award is presented to members that have demonstrated a consistently high level of work for the entire organization. Additionally, they have shown that they share the vision, mission, and ideals of TRMN and that they strive to obtain it within their areas of responsibility in the club. This is the third level of lands awarded, and is usually awarded to a member who is already an earl or countess.
The policy, as of 2017, is to award a land with a different name than that of the county which the earl or countess had held before.