During World War II, Britain ordered the massacre of all family pets!
750000 pets were killed within a week to overcome food shortage in a starting war!

What to do with your pets once a war brakes out? During WWII, the British government, concerned by food shortages, created the National Air Raid Precautions Animals Committee in 1939, which drafted a notice named Advice to Animal Owners.
The pamphlet, which came with an advertisement for a specific type of gun, said: “If at all possible, send or take your household animals into the country in advance of an emergency […] If you cannot place them in the care of neighbours, it really is kindest to have them destroyed.”

The reaction of the British population was radical. Within the course of a week, 750,000 family pets were “destroyed.”
Also, please note that this took place during the summer of 1939 — i.e., before Germany invaded Poland, and during a time when the British government could have done a lot more damage to Nazi Germany if they simply attacked them instead of massacring all family pets and printing posters for when the Nazis conquered London.
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