In a (strange) dinner table discussion, my brother is insisting that a driving cause behind the 1857 Indian Rebellion ('Sepoy Mutiny') was a rumour - one which was apparently discovered to be false - that cartridges supplied to Sepoy troops were made with a mix of cow and pig fat without the knowledge of said troops. With most Sepoys being either Muslim or Hindu, he states, this would be of great offence.

Frankly, I'm suspicious of this explanation. It seems far too convenient. He acknowledges other causes without elaborating, but I suspect that he greatly overstates the above rumour as a convenient explanation. (He is known for pro-Imperialist 'Teaaboo' views.)