The revolt of 1857 started with the rumour of the greased cartridges that were used in the army of the East India Company. It was rumoured that the grease was made of the fat from cows and pigs, which made the cartridges taboo for both Hindu and Muslim soldiers in the Company's army.
The revolt started in Barrackpore when sepoy Mangal Pandey refused to use the cartridges. Pandey was executed as punishment for his mutiny. From there, the rebellion spread to Meerut, Delhi and other parts of North India like Jhansi, Kanpur and Lucknow.