On a hill near the village of Itter in Austria sits a small castle that during World War II was seized by the Waffen SS and converted into a prison camp for high-profile prisoners valuable to the Nazis. On May 3rd, 1945, an imprisoned Yugoslav communist resistance member left the castle on the pretense of an errand for the commander to find the Allies and ask for their help in liberating Itter Castle and its prisoners. He found units of the U.S. Army, but they were unable to fight their way to the castle.
Meanwhile, the German commander and the guards abandoned the Castle, and the prisoners contacted the Austrian resistance in the town of Wörgl, five miles away. This town had been abandoned by the German army (Wehrmacht) but was reoccupied by the SS. The leader of the resistance was a German major, commander of the remains of a unit who had ignored an order to retreat and instead joined the resistance. They weren’t strong enough to challenge the SS, but they contacted a reconnaissance unit of the U.S. Army. Together the U.S. soldiers and Austrian resistance organized a relief force, rescued the Castle, then fought off an SS counterattack the next morning.
This has been described as the strangest battle of World War II. It was fought five days after Adolf Hitler had committed suicide and was the only battle where Americans and Germans fought together.
For all the details, see “In the final days of WWII, German Wehrmacht soldiers fought alongside US Army troops to defend a medieval castle from the Waffen SS” by Ian Smith (https://www.thevintagenews.com/2016/08/22/priority-19/). The photo came from that site. Special thanks to Gary Covington for submitting this.