...at east the city was besieged, enclosed in a ring of foes. The Rammas was broken, and all the Pelennor was abandoned to the Enemy. –The Return of the King
When Revealed: Each player takes control of each ally he owns in the staging area and exhausts it. The first player adds Minas Tirith, Grond, and The Witch-king (Captain side faceup) to the staging area. Each other player searches the encounter deck and discard pile for a different enemy and adds it to the staging area. Shuffle the encounter deck.
...since the middle night the great assault had gone on. –The Return of the King
The White City Besieged gets +4 quest points for each player in the game.
The players cannot travel to Pelennor locations.
Forced: When an enemy is destroyed, place progress on this stage equal to that enemy's total 
(progress must be placed on the active location first).
Horns, horns, horns. In dark Mindolluin's sides they dimly echoed. Great horns of the North wildly blowling. Rohan had come at last.
–The Return of the King
When Revealed: Set the Witch-king aside, out of play. Each player searches the top 10 cards of his deck for an ally that matches the sphere of a hero he controls and put it into play under his control. Each player shuffles his deck.
...the hosts of Mordor wailed, and terror took them, and they fled, and died, and the hoofs of wrath rode over them. –The Return of the King
Progress cannot be placed on this stage by questing successfully is instead assigned as damage among enemies in play. (Progress must be placed on the active location first.)
Forced: At the end of the quest phase, advance to stage 5A.
And now the fighting waxed furious on the fields of the Pelennor; and the din of arms rose upon high, with the crying of men and the neighing of horses.
–The Return of the King
When Revealed: The first player adds The Witch-king to the staging area (Sorcerer side faceup). Then, he searches the encounter deck and discard pile for a Fell Beast and attaches it to The Witch-king, if able. Shuffle the encounter deck. Each other player reveals an encounter card.
The Witch-king and shadow cards deal to The Witch-king are immune to player card effects.
Forced: When an enemy attacks and destroys a character, deal 1 damage to Minas Tirith.
This stage cannot be defeated unless Aragorn is in play and The Witch-king is in the victory display. If the players defeat this stage, they win the game.
Setup: Set each Harad enemy recorded in the campaign log aside, out of play. The first player attaches Andúril and Banner of Elendil to Aragorn and set him aside, out of play. Add The Corsair Fleet to the staging area (Gondor side faceup) and place X resources on it, where X is the number recorded in the campaign log. Remove each burden with the following burden set icons from the encounter deck, then flip this card over.
Forced: When the players advance to stage 5B, add each set aside Harad enemy to the staging area.
Resolution: Add 1 copy, per player, of Wraith on Wings to the campaign pool. The players have earned those burdens. If Esquire of Gondor or Esquire of Rohan is attached to a hero, that hero's controller has earned that boon.
Thus came Aragorn son of Arathorn, Elessar, Isildur's heir, out of the Paths of the Dead, borne upon a wind from the Sea to the kingdom of Gondor.
–The Return of the King
6
6
14
Immune to player card effects.
Cannot be optionally engaged or take damage.
Forced: At the beginning of the quest phase, discard cards from the encounter deck until an enemy is discarded. Add the discarded enemy to the staging area.
6
6
14
Only the engaged player can declare attackers against the Witch-king.
Forced: At the beginning of the encounter phase, The Witch-king engages the first player. Then, it makes an immediate attack.
"No living man may hinder me!" –The Return of the King