The Republic of Upper Bavaria is a nation formed from the ruins of Nazi Germany.
Following the impact, which lit the sky over Germany, Hitler was evacuated from Berlin, as panicked civilians overwhelmed the Infrastructure of the City. Hitler arrived in the Eagle's Nest within a few hours of the impact, and took to his bed, overwhelmed by the shock. He would not leave his bed until his death, 4 months later.
In the time between Hitler's arrival in Bavaria, and his death, the SS units designated for his protection took control of the region. They shut the borders, and abandoned the rest of Germany to its fate. They ruled with an Iron Fist, and many Bavarians were sent to their deaths for disputing the SS orders to surrender their food to their SS superiors. But the SS only maintained control for as long as Hitler remained alive. The Wehrmacht forces in the area, under Field Marshall Rommel greatly outnumbered the SS, and they made no secret of their distaste for the SS.
In October, 4 months after the Impact, Hitler, now severely mentally disabled, awoke, and walked, as if in a dream, out onto a Balcony over looking the Mountains below, and jumped. Reports suggest that he bounced on impact. The SS was distraught. They had Wehrmacht forces on all sides. They did the only thing they could, and retreated to the Eagle's Nest. The Chateau could be held almost indefinitely against any attacking force. By now, the Luftwaffe had been widely recalled to Germany, and Bavaria specifically, by order of the Führer, although it was now grounded by ash, and of no use to the Wehrmacht forces. So the Wehrmacht simply ignored the SS, leaving a Panzer at the foot of the Mountain, trapping the SS. The SS, without water, was dead within a few days.
Rommel, upon gaining command, began allowing refugees to enter Bavaria. At this point, the extent of the damage done by the impact was unknown. The population swelled. When the Summer was weak, and few crops grew, the border was shut. Bavaria was closed off once more. The Wehrmacht had to retreat back from most of Bavaria, as the areas became drains on their resources. By the time the Great Winter ended, the Wehrmacht controlled only Upper Bavaria. But that wasn't all they wanted to control. They had their eyes on the prize. The Wehrmacht had a target now. They wanted only one thing. To unite Germany. And soon, they would begin their quest.