In a large saucepan, combine red wine, cranberry juice, sugar, water, lemon juice, and stick cinnamon. Heat just until bubbly around edges; reduce heat. Simmer, uncovered, for 10 minutes. Remove cinnamon with a slotted spoon. Stir in brandy, if desired. Carefully pour punch into a heatproof punch bowl; garnish with lemon slices, if desired. Ladle into heatproof cups. Makes 12 to 14 (4-oz.) servings.