In The Lord of the Rings: The Return of the King, Aragorn reaches the port city of Pelargir after passing through the Paths of the Dead.
Aragorn seeks the help of the Dead Men of Dunharrow because they once broke an oath to serve Isildur. After the Dead defeat the Corsairs at Pelargir, Aragorn releases them from their curse. He then captures the Corsair ships and uses them to transport an army toward Minas Tirith.
The film presents this sequence as a major turning point in the War of the Ring. Aragorn’s arrival by ship at the Battle of the Pelennor Fields surprises Sauron’s forces and strengthens Gondor’s defense. Pelargir is easy to confuse with Minas Tirith, which is the city under siege, or Osgiliath, a strategic city farther upriver. Pelargir’s importance comes from its harbor and its connection to Gondor’s southern waterways.