It was no secret that the French wanted some beef with the Prussians in 1840, as there was the Rhine Crisis, as France demanded the borders of 1806, where the Rhine was the territorial border between the two states. Before 1840 some politicians already had a very aggressive attitude towards Prussia because of the treaty in 1814 and the Congress in Vienna 1815.
This tension was suppressed by a new minister of foreign politics in 1841, escaping a possible war.
Imagine, this never happened. As both nations have created enormous patriotic tension towards the other state a war started and both armies fought so devastating, that the entire region west from the Rhine suffered mass murder and devastation, like in the 30-years war.
Would it be possible in the aftermath that both states agree on having peace but none want to take responsibility over this region? As building it up again would be too costly, none of the parties want to claim ownership now, as the civilians also have a very negative attitude towards them. So it becomes no mans land, and a faction of paramilitaries take over control, declaring independence, which is fine for for France and Prussia.
Is this a realistic scenario? What should/could I improve?