What was the immediate cause of the Revolt of 1857?

The immediate cause of the Revolt of 1857 was the introduction of the Enfield rifle by the British. The cartridges had to be bitten off before use, and it was rumoured that they were greased with cow and pig fat. This angered Hindus, for whom the cow is sacred, and Muslims, for whom the pig is taboo, leading them to believe that the British were trying to defile their religions.