The Main Squeeze

In a pitcher, combine the wine, lemon juice, gin, simple syrup, and both types of orange bitters. Chill in the refrigerator for at least 2 hours, until cold. Fill an old-fashioned glass with ice and pour 4 ounces of the mixture into the glass. Top with 1 1/2 ounces of the ginger beer, stir gently, and garnish with 2 of the lemon slices, each pressed against the side of the glass with the handle end of a barspoon or a chopstick. Repeat with the remaining ingredients. Serve at once.