What is "ban of the empire"

Ban \Ban\ (b[a^]n), n. [AS. bann command, edict; akin to D. ban, Icel. bann, Dan. band, OHG. ban, G. bann, a public proclamation, as of interdiction or excommunication, Gr. fa`nai to say, L. fari to speak, Skr. bhan to speak; cf. F. ban, LL. bannum, of G. origin. [root]86. Cf. Abandon, Fame.]

1. A public proclamation or edict; a public order or notice, mandatory or prohibitory; a summons by public proclamation.

2. (Feudal & Mil.) A calling together of the king's (esp. the French king's) vassals for military service; also, the body of vassals thus assembled or summoned. In present usage, in France and Prussia, the most effective part of the population liable to military duty and not in the standing army.

3. pl. Notice of a proposed marriage, proclaimed in church. See Banns (the common spelling in this sense).

4. An interdiction, prohibition, or proscription. ``Under ban to touch.''
   --Milton.

5. A curse or anathema. ``Hecate's ban.''
   --Shak.

6. A pecuniary mulct or penalty laid upon a delinquent for offending against a ban; as, a mulct paid to a bishop by one guilty of sacrilege or other crimes.

   Ban of the empire (German Hist.), an imperial interdict by which political rights and privileges, as those of a prince, city, or district, were taken away.