Train reservations

Only if you want to save a lot of money by buying a nonrefundable ticket in advance.

Are you using tickets or a Eurail pass?

Is the train a local stopping TER train, or an express high speed TGV?

If it is a TGV, all seats are reserved. If you ride a TGV with tickets the reservation is included. If you ride a TGV with a Eurail pass you must buy expensive passholder reservations; in that case if you board without you will be treated as having no ticket even though you have a Eurail pass, and will have to pay a very large fine, and may be required to leave the train or buy a new full fare ticket in addition to the fine.

From your previous posts, I understand that you have taken TGVs before and expect that you'll choose that direct service again. (Non-TGV options on this route require one or more connections and still need a seat reservation for at least one leg of the trip.) If you are thinking of a France Rail Pass, then we recommend making the TGV reservations at the same time that you buy it, $12 or $23 per person on domestic routes, depending on how full the train already is. Note that the 20% off sale on this pass ends tomorrow at 5 p.m. Eastern time. Point-to-point tickets booked well ahead can be less than half of the full fare, starting from $46.