The four most gruesome situations I have encountered in my research:

#1 During the French and Indian War, in the Ohio territory, an English officer was captured by the local Native American tribe (Shawnee?), just because he was in the "wrong place at the wrong time". He was tortured in unspeakable ways, the most vivid in my memory being his intestines were cut from his body and slowly unraveled and rewound on a pole as he was forced to walk through a huge bonfire.

#2 An American hospital ship during WWII, housing both British and American nurses, was torpedoed and the British side of the ship was burning uncontrollably while simultaneously taking on water. A British nurse broke through an interior wall enough to stick her head through and scream for help. There was no help. A 14 year old British "cabin boy" could do nothing to help her or her comrades, so to put her out of her misery he beat her to death with a large piece of wood he found in the wreckage.

#3 In Russia, Polish refugees were originally happy to see the Russians because it meant the German occupation was over. A mother and daughter duo (they were the final survivors from a family of eight)had made it this far but now the mother was lying on the floor of an abandoned and burned out shell of a barn dying of typhoid fever. The daughter, 11 years old at the time, watched as marauding Russian soldiers took turns raping her mother as she lay dying from typhoid.

#4 A 17 year old Belgian girl was active in the local resistance movement and had never had a serious encounter with the Germans. Her parents and brother were active as well. The family was betrayed and the mother, father and daughter were arrested and sent to three different concentration camps. The son was never caught. The good news is all four were reunited after the war. The bad news is the young girl was a victim of Mengele but survived. Mengele, and his band of goons, tried to sterilize her using x-rays (although she was badly burned it didn't work and had a healthy baby boy some 15 years later) and the worst part was one of her thighs was injected with the gangrene germ and her entire leg turned black. Her infected leg was then cut open to the bone and packed with gauze to soak up the infection. This so-called "care" lasted for months and the miracle is this young woman survived and her leg healed but she walked with a limp.

From Code Name Christine Clouet... p. 39

Some definitions:
Offlag- an officers camp
Stalag- a camp for enlisted soldiers and non-commissioned officers

From Code Name Christine Clouet... p. 33

The Vichy regime defined a Jew as any person with three Jewish grandparents or two grandparents and a Jewish spouse. Jews were forbidden to hold or run for elective office; work in the civil service; the judiciary or as officers in the army. Jews were not permitted to teach school; work in publishing; films or the theatre.

Continued from Code Name Christine Clouet...p. 26

#3. Italian Occupied Zone: including Savoy, Nice & Corsica. "...The Italian occupation was much milder than the German."

#4. & 5. Forbidden Zones: the coast along the English Channel and the Atlantic ocean and an area in the NE abutting the Occupied Zone. These zones were under German battlefield command and fortified against attack.

#6. Alsace and part of Lorraine were immediately annexed by the Reich, which tried to "Germanize" the population by expelling all those who wouldn't or couldn't assimilate. The tens of thousands of people expelled were given the choice of moving to Germany or the Free Zone. Most chose the Free Zone.

#7. The French POW camps in Germany: approximately 1.8 million men behind the barbed wire.

Along the seven zones, all civilian traffic, all telegraph and telephone communication were prohibited. To cross a frontier you had to have a Ausweis, a pass, from the German command.
Mail was forbidden as well except for specially prepared postal cards.