This is from memory from college days long ago, so forgive me if details are wrong.

I remember India was under British control and then the British came out with some new gun and powder for their Indian army.

The gun powder came wrapped in paper packets soaked in pig and cow fat. The infantry had to tear open the package with their teeth.

As the Indian forces were mostly Hindu and Muslims, putting the animal fat in their mouths was considered sacrilegious.

The army rebelled and England lost control over India.