Combine the juice and cranberries in a blender, and puree until things are as smooth as possible. Strain into a pitcher, and add your whole bottle of wine. If your pitcher isn't big enough, just eyeball half of each into two pitchers. My mixture fit perfectly into the giant 2 quart mason jar that I had in my pantry.

To make one spritzer: Fill a tall glass halfway with ice. Then add 1 cup of your wine mixture (the glass will be about 2/3 full now). Top off with soda water, and garnish with the cranberries and rosemary.