Prepare a small campfire and allow to burn for about 1 hour.
Preheat Dutch oven for 15 minutes over hot coals.
Meanwhile, beat together eggs, milk, vanilla, and cinnamon in a medium sized bowl. (Tip: You could prepare this in advance and store in a sealed jar or bowl until ready to serve.)
Quickly dunk the bread pieces into the egg mixture to coat.
Remove lid from Dutch oven and place a stick of butter at the bottom. Use the second stick of butter to coat the insides of the pot (using a long stick or skewer to move it around the hot pan).
Melt butter in heated Dutch oven. Add brown sugar into the melted butter and stir with a long wooden spoon to combine.
Once the sugar-butter mixture has begun to caramelize, add the sliced peaches and stir to coat.
Add the egg-soaked bread cubes on top of the peaches.
Return lid to Dutch oven and replace over hot coals beside the campfire.
Bake for 35-45 minutes, rotating often, and adding more hot coals as needed. Check occasionally to ensure the bread is not burning.
Let cool 10-15 minutes before serving.
Recipe adapted from: https://www.bigoven.com/recipe/peachy-dutch-oven-french-toast/843039