The Company administration introduced the new Enfield rifle whose cartridge had a greased paper cover. It had to be bitten off before it could be loaded into the rifle. A rumor that the cover contained cow and pig fat started doing the rounds. The cow was sacred to the Hindus, and the pig was taboo for the Muslims. As a result, both religious groups felt insulted and cheated. The cartridge incident proved to be the final straw as the sepoys were already seething with discontent because of a variety of other social, economic and political policies of the British Government. Finally, on 29 March 1857, Mangal Pandey, a sepoy at the Barrackpore cantonment, refused to use the cartridges. As a result, he was hanged to death. The news spread like wildfire and on 9 May, 85 soldiers at Meerut too refused to use the new equipment. They were court-martialled and sentenced to 10 years. To further buttress the point, they were stripped in front of their colleagues and thrown into jail. This resulted in the other sepoys rising in revolt. They ransacked the jail and freed their comrades and even cut off the telegraph lines to Delhi. Even the European officers were not spared and their houses were set on fire. Thus began the revolt of 1857.

The Indian Rebellion of 1857 had diverse political, economic, military, religious and social causes. ... The spark that led to a mutiny in several sepoy companies was the issue of new gunpowder cartridges for the Enfield rifle in February, 1857. A rumour was spread that the cartridges were made from cow and pig fat.

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Causes of the Revolt of 1857
The Revolt of 1857, also known as the Sepoy Mutiny, was a significant uprising against British rule in India. Its causes were multifaceted, rooted in social, political, economic, and military grievances.
Political Causes
- Annexation Policies: The British annexation of territories through the Doctrine of Lapse discontented local rulers and led to a loss of autonomy.
- Discontent among Princes: Many Indian princes were unhappy with their diminished status and influence under British dominance.
Social and Religious Causes
- Cultural Insensitivity: The British disregard for Indian customs and religions created resentment among the local population.
- Introduction of New Enfield Rifles: The use of animal fat in rifle cartridges offended both Hindu and Muslim soldiers, leading to widespread anger.
Economic Causes
- Heavy Taxation: Excessive taxation and exploitation of resources led to widespread poverty and discontent among peasants and farmers.
- Destruction of Local Industries: The British policies favored British goods, leading to the decline of traditional Indian crafts and industries.
Military Causes
- Pay and Service Conditions: Indian soldiers, or sepoys, were dissatisfied with their pay, treatment, and the lack of opportunities for promotion.
- Discrimination: There was a clear distinction between British and Indian soldiers, which fostered resentment and feelings of inferiority among the sepoys.
Conclusion
The Revolt of 1857 was not merely a military uprising but a culmination of various grievances against British rule, reflecting deep-seated issues that had been festering in Indian society. Understanding these causes provides insight into the complexities of colonial India and the struggle for independence.