Why was the army of the dead at Minas Tirith?

[Nerwen]

Originally Posted by TheOrcWithNoName

Personally I think they were included due to time & money constraints. PJ either didn't have the necessary budget to film the true battle in full, and neither did he have the additional time. So he took a few liberties with the book and let the Flubbers do their stuff in a matter of seconds rather than minutes.

I've wondered myself whether the Army of the Dead was originally going to have extra-special effects (instead of the rather cheap and nasty look it ended up with), so that PJ decided to feature it as often as possible, whether or not it made sense... and then it turned out that would cost too much.