What is the theme in Guards! Guards! by Terry Pratchett?

Love for country is another theme. The city of Ankh-Morpork is described in such a way that it seems no one could care for it. The Night Watch conduct themselves in a sloppy way and don't enforce laws or take care of the city. It seems they don't care about anything but then the dragon starts coming into the city and takes over. Several times in the story Captain Vimes states that things like that can not be happening in his city. He admits that while the city may not have been perfect, he refuses to let it be taken by the dragon. He suddenly becomes willing to fight for something that before he didn't even act like he enjoyed.