Too perfect: Digital warriors thought for themselves – and their first thought was to run away It's the greatest and most spectacular battle in the Lord of the Rings trilogy. But filmmakers faced one surprising challenge – how to keep the computer-generated soldiers from fleeing the battlefield. Director Peter Jackson had laid down his requirements for the Battle of Pelennor Fields – the climactic engagement in The Return of the King in which the heroic defenders of Middle-Earth face the overwhelming might of Sauron and his armies of Darkness. Jackson wanted the computer-generated antagonists to have absolute authenticity on the…