The greased cartridges of the Lee Enfield rifles came in pouches that had to be torn by the teeth of the Sepoys. It was rumoured that the grease was animal fat. So this was against the religious sentiments of the Hindu soldiers. So a Brahmin soldier named Mangal Pandey shot dead his battalion chief. That was the beginning of the Sepoy Mutiny in Murshidabad in the state of West Bengal. Soon it spread to Delhi. Now it's called the Indian War of Independence because Sepoy Mutiny is a British term.
So the points are;
1. The farmers were forced to cultivate the dye indigo for the British uniforms instead of normal crops.
2. Doctrine of Lapse - if a ruler had no natural heir, their kingdom would be taken over by the British.
3. High taxes.
4. Greased cartridges.
Hope this helps:)