Warm cider and rum punch

Ingredients:

 8 cups apple cider
1 apple, thinly sliced crosswise
1 orange, thinly sliced crosswise
2 cinnamon sticks
1-inch piece fresh ginger, peeled and thinly sliced
2 cups dark rum

Preparation:

In a large pot, combine apple cider, apple slices, orange slices, cinnamon sticks, and ginger.
Bring to a boil over high; reduce to a simmer and cook 5 minutes.
Keep warm over low, up to 2 hours.
Remove from heat and stir in rum. 
Transfer to a punch bowl; serve warm.