Battles

[The Might]

Well, all I can think about is the conversation between Gorbag and Shagrat.
Let me get the quote.
Ok, here it is:

[FONT=&quot]There's no grief in that; but think-there's someone loose hereabouts as is more dangerous than any other damned rebel that ever walked since the bad old times, since the Great Siege. Something has slipped.'[/FONT]

So the Orcs refer to the Siege of Barad-dûr as the Great Siege.