Heat oven to 400° F.
In a large saucepan, over medium-high heat, fry the bacon until almost crisp. Spoon off and discard all but 1 tablespoon of the drippings. Add the leeks and cook, stirring occasionally, until tender, about 3 minutes. Add the potatoes, corn, wine, cream, salt, and pepper. Bring to a boil. Transfer to an 8-by-11-inch baking dish or shallow 2-quart casserole. Nestle the cod pieces into the chowder mixture. Top with the crackers and cover loosely with foil. Bake until the fish is cooked through, about 20 minutes.