Reply #14: Actually, no [View All]

The trek from Minas Tirith (not Osgiliath) to the Black Gate takes the better part of a week or so in the books. This is necessary because Sam and Frodo are waylaid and having a devil of a time getting through Mordor to Mount Doom. If the twin climaxes of the confrontation and battle before the Black Gate and the end of Frodo's task are to coincide, the good guys have to be held up, and the journey north to the Black Gate has to take some time.

The journey north is also designed to distract Sauron's attention after the battle for Minas Tirith. At all costs, the good guys know that Sauron can't be left to his own devices in Mordor in the aftermath of his army's defeat. So they undertake a hopeless task, traveling up the long road to the Black Gate along the border with Mordor, knowing that Sauron's spies and attention will be riveted on the party's progress, and not on what might be going on nearer at hand.

Unfortunately, this delaying tactic doesn't make for a good movie. Travel sequences aren't very interesting to film or watch, so the journey to the Black Gate is horribly foreshortened. The trip Sam and Frodo take from the tower above Cirith Ungol to Mount Doom is also cut a lot shorter than it was in the book. In the movie, it's almost as if the two sites are next to each other, but in the book, Frodo and Sam stumble in disguise with an orc horde for over a week, almost to the Black Gate inside Mordor before heading south to Mount Doom.