This would be for 2027....yes, not a typo, next year. I'm thinking about a trip to Normandy (4-5 days Bayeux, including Carentan, Caen, and maybe a side trip to Mont Saint-Michel), then to Bastogne (2-3 days with a possible day trip to Wiltz), Colditz, and Berchtesgaden. Currently, this would be a solo trip, but I would love to find someone interested in this to travel with. I'm in the early stages of planning and it is almost a year away (currently thinking about June time frame), but would love to discuss with someone who shares the same interest. All travel would be done by rail....I don't anticipate renting a car.
whilst waiting for volunteers, have you tried to create the rail itinery? use www.bahn.com 2027 isn't loaded until december but you can get the idea using 2026. There are some long and complicated rides in this plan. I'm not saying you shouldn't do it but it's probably best to know what you are in for before getting too involved with somebody else.
ps don't pay too much attention to fares quoted by the above website, for something this big there will be an alterntative....
There are a few tour companies that do "Band of Brothers" tours that cover some of your proposed itinerary.