Place bacon in a large pot, and cook over medium heat until crisp. Stir in onion, leek, carrot, and garlic; cook until the vegetables are soft, about 8 minutes. Pour in chicken broth. Stir in split peas, bay leaves, and rosemary. Bring to a boil. Reduce heat to low; cover, and simmer until peas are cooked, about 1 hour, stirring occasionally.
