Wash collard greens thoroughly in cold water; drain well. Remove stems and thick ribs; discard. Trim bruised leaves. Coarsely chop leaves to measure 6 cups; set aside.
In a large cast-iron or heavy skillet, cook bacon until crisp. Remove bacon from skillet; reserve 2 tablespoons fat and discard the remaining. Drain bacon slices on paper towels. Crumble or chop. Set aside.
In same skillet, cook onion in reserved bacon drippings until tender. Add collard greens. Pour wine over the greens. Bring to boiling; reduce heat. Simmer, covered, for 10 minutes. Uncover and cook about 5 minutes more or until most of the wine has evaporated and greens are just tender. Transfer mixture to a serving bowl; sprinkle with reserved bacon. Serve immediately. Makes 4 servings.