Were rifle cartridges greased with aimal fat the key cause of the sapoy rebellion?

One version of the story of the Sepoy Rebellion was that a rumor started that cartridges for the muzzleloading rifles issued to the native soldiers in India had bullets lubricated with beef tallow, another that lard (pig fat) had been used. These cartridges were used by biting the paper cartridge to open them before pouring powder down the barrel. Many of the soldiers were Hindu, and regarded the cow as a sacred animal, and believed this was an effort by the British to "break their caste"- or disgrace them. The Muslim soldiers believed pigs (and pig fat) to be unclean, and prohibited by their religion.

In fact, the cartridges were lubricated with neither tallow nor lard, but the British forces failed to control the rampant rumors, ordered to troops to use the cartridges, and took disciplinary action against the Sepoys when they refused.