I heard this story on QI (series F, episode "Fight or Flight"). I have supplemented it with a little research of my own. If anyone knows anything else about it, please write in.
In July 1870, France went to war with Germany in what is now called The Franco-Prussian War. It went badly for France. By mid-August, the French army had suffered several embarrassing defeats. By September, just two months later, Emperor Napoleon III was captured and his wife and only son went into hiding. The French Empire was over. Unlike most wars where the optimistic young soldiers tell their sweethearts, "It'll be over in a month" only to have it drag out for years, this one actually WAS. Ish.
Paris went under siege for the next five months. First the Prussians started shelling the city. They shelled them for 23 days. But the Parisians just put some sandbags around the Louvre, packed up all their valuable artwork, moved it underground so it wouldn't get damaged, and went, "Is zat ze best you 'ave, Fritz? We do not care about your puny shellings."
The Prussians were like, "Bullets may not scare you, but there is one thing that frightens a Frenchman–NO FOOD." The French went, "Le gasp! No, we will be strong. We will not cow to the Germans, even if we must make the ultimate sacrifice of our fine cheeses and dry wines." (Okay, I'm totally trivializing this–we're talking about the level of hunger where people eat their pets, and then rats, and then their own shoes just for the salt.)
They had run out of horses to eat, and then they ran out of cats and dogs, and then even the rats were growing scarce. So they ate the zoo. The elephants, Castor and Pollux, provided a lot of meat, but not any pleasure to the citizens, since the elephants were the pride and joy of Paris. Here is an illustration of the zoo animals being divvied up. That's quite the butcher shop selection.
The only animals that were spared (although I'm not sure how the animals themselves escaped death by starvation) were the lions and tigers, because they were difficult to approach and kill, and the monkeys because of "some vague Darwinian notion that they were the relatives of the people of Paris and eating them would be tantamount to cannibalism" (The Siege of Paris 1870-1871, pg 63).
However, in true French style, some of the meat was given to fine restaurants where they transformed it into elegant dishes for its upper class citizens. They even had daily menus drawn up to make the wealthy Parisians feel as close to normal as possible.
A normal menu before they ate the zoo animals contained some of these items:
Emincé de rable de chat. Sauce mayonnaise. [Sliced maple cat in mayonnaise]
Epaules et filets de chien braisés. Sauce aux tomates. [Shoulders and fillets of braised dog in tomato sauce]
Salamis de rats. Sauce Robert. [Rat salami in Robert sauce (whatever that is. Hopefully not someone named Robert)]
Gigots de chien flanqués de ratons. Sauce poivrade. [Haunches of dog flanked by mice in pepper sauce]
Begonias au jus. [Begonia flower juice]
Plum-pudding au rhum et à la Moelle de Cheval. [Horse marrow plum pudding with rum]
Here is a menu with items from the zoo:
Here are a few highlights:
Tête d'âne farcie [Stuffed donkey head]
Consommé d'éléphant [Elephant soup]
Le chameau rôti à l'Anglaise [Roast camel]
Le civet de Kangourou [Kangaroo stew]
Côtes d'ours rôties sauce poivrade [Bear in roasted pepper sauce]
Cuissot de loup, sauce chevreuil [Haunch of wolf with deer sauce]
Le chat flanqué de rats [Cat flanked with rats]
La terrine d'antilope aux truffes [Antelope terrine with truffles]
The Germans got their victory in January of 1871 and honored the armistice by sending trains of food into Paris. If I had been the Germans, I would have sent them another zoo, because these dishes sound DELICIOUS.