What were the causes of discontent …

The mutiny in the sepoy ranks became a rebellion in 1857. There was general defiance of all kinds of authority and hierarchy. 

Following were the reasons for discontent among the soldiers:

1. Fear of New Cartridges: The sepoys were provided with bullets that were coated with the fat of cows and pigs. Before use, the soldiers had to bite these bullets. So they feared that it would corrupt their caste and religion.
2. Grievances about Leave and Promotions: The sepoys were not granted leaves easily. They were also paid lower salaries as compared to the British soldiers. They were not given due promotions which enraged the soldiers and nurtured a sense of discontent among them.
3. Grouse Against Misbehaviour and Racial Abuse: Earlier, the British officials had very friendly relations with the sepoys. They joined them in their leisure activities and talked to them in the local language. They also familiarised themselves with their customs and culture. They posed themselves as fatherly figures to all the Indian soldiers. But after the 1840s, there was a change for the worse. The British officers started considering themselves as superior. This grouse about the increasing misbehaviour and racial abuse on the part of their white officers were communicated back to the villages. 
4. Nexus between Soldiers and Villagers: Awadh was the nursery of the Bengal Army because a majority of the sepoys of the Bengal Army were recruited from the villages of Awadh and eastern Uttar Pradesh. So these soldiers had a close relationship with the villages. Such a link between the two had grave implications during the mutiny. When the sepoys defied their superior officers and took up arms they were joined very swiftly by their brethren in the villages.