It only became clear to me at the climax of the movie, but, looking back, I should've seen it coming all along. I mean, just consider the progression of events:
A known, but untouchable, group of criminals have terrorized Gotham City, until a heroic aggressor finally steps up for the good citizens and starts aggressively hunting down the evil, in a large cloud of public praise.
Fittingly, the specific first act of violence in the film is initiated and orchestrated by an insane, unkempt radical with a propensity for making home videos. This, effectively sets off the war that's about to be waged in the film.
Said heoric aggressor, namely, Bruce Wayne (or W., B., as I like to call him), funds his war on terror by misappropriating large amounts of hard-earned corporate money to his own personal weaponry department, creating never-seen-before technology to wage war with.
When one of the foreign conspirators (who is actually only marginally connected to The Joker) manages to escape back to his home country, Geor... er, I mean, Batman launches a top secret mission in which he infiltrates said foreign territory and illegally extradites the suspect, throwing him into a local prison. He later dies, but not before immeasurable amounts of cash are burned for the purpose of killing him.
Despite this public "victory", Public Enemy #1, is still at large, so Batman results to torturing suspected criminals for wild grabs at information. This marks the start of an epic physical chess game where The Joker and Batman keep one-upping each other in an effort to gain supremacy (all right, so, this part is slightly exaggerated).
The battle escalates to the point where the public begins to urge Batman to step down, in order to stop the madness, realizing that Batman's reign only attracts terror, as much as it deters it. Public favor suddenly starts to shift towards a young, highly charismatic politician, who begs for people to believe in him.
Batman begins to consider stepping down, even going so far as joking to his ancient, right-hand man that he'll go down with him. This all changes when The Joker eludes capture yet again, prompting our hero to initiate a controversial movement that allows him to access all the public's cell phones and geographic locations. Due to his actions, his African-American confidant and chief of his defense department nearly resigns in disgust.
Finally taking a swerve into speculative fantasy, Batman captures The Joker after a confrontation in a construction site, but not before The Joker and his cohorts leave a large trail of bodies behind.
Realizing that he partially was responsible for the trail of destruction, our hero heroically accepts responsibility and even is willing to paint himself as a villain, selfessly and heroically paving the way for the aforementioned young upstart politician to take his hero's mantle, and deliver the message of hope and change to the world.
And thus ends
George W. Bush, may you be chased by men and dogs.
The Dark Knight: 8/10