In a large Dutch oven over medium heat, cook the bacon until crispy. Drain away all but about 2 tablespoons of the bacon grease, then return the pan to the heat. Add the chopped onion, and cook in the bacon grease until the onion is translucent, about 7 to 8 minutes. Add the beans, broth, salt, and pepper. Bring the broth to a boil, and then reduce the heat to a simmer and cook about 45 to 60 minutes or until tender.