I read a book several years ago called “ashes of honor”. It was by a French soldier who joined the Waffen SS during WWII. His outfit was all French.
They fought in some horrific battles against the Russians and I am pretty sure they were the most decorated battalion in the German military.
On the other hand, I remember reading that the French Kings at one time had as their body guards a group of 100 mercenaries from Scotland. They were called the “Scots Guard”.
The French volunteer SS unit (”SS Freiwillinge Division Charlemagne”, I think) was one of the German units that chose to stand and die in the final battle for Berlin in 1945.
During WW2, the Finn’s had Waffen SS units fighting the Soviets. They were decorated several times for their bravery, once even by the pervert Himmler. The Finn units were allowed to resign and go home when Finland and USSR declared an armistice ending the Continuation War, 25 June 1941 – 19 September 1944. In August 1944 the USSR had had another go at conquering Finland, they went in deep and hard before tiny Finland once again gave them a very bloody nose and stopped them once again. I think the Russkies were just damn glad to be done with it, for they knew even if they won, they would be in for a long and bloody protracted guerilla war with the Finns operating out of Sweden and Norway. This would have perhaps given ideas to other conquered countries to enter into guerilla wars of their own. Not to mention the USSR still faced almost a year of hard slogging against the Nazis.
Some of the Finns hated the Russians so much, they served in the SS to the bitter end