Re: Why did the League of Shadows want to destroy a peaceful city?
I think Bane is probably the most underdeveloped villain in the trilogy but there is enough in his dialogue to suggest what Bane's motives are. We know he spent most of his life in a prison somewhere far from America, he views the 8 years of peace as "borrowed time," and the line about "the next era of Western civilization," are telling. He shares the disgust for Western decadence, which is even more prominent in TDKR. Like Ra's, Bane does not think Gotham is redeemable, it doesn't matter what is happening on the surface, it is rotten to the core. Learning of the Dent lie is just further proof of what he already believes. I think it could have been elaborated on but it's implied that a lot of Bane's army is not his mercenary group, it's the poor in Gotham looking for work and then those rallied by his speech. The class warfare is Bane's version of the fear toxin, which suggests it is something he personally identifies with. "It was the best of times, it was the worst of times," could have been elaborated on a bit more.