The immediate event which angered the sepoys was about the ammunition for the new rifles they had to use were Enfield rifles. The cartridges that were used in the new rifles had to be bitten open. The Muslims were angry because they thought that the paper cartridges had pig fat in them. This was because Muslims believe that pigs are unclean. Hindu soldiers were angry because they believed the cartridges had cow fat in them. On January 27, Colonel Richard Birch ordered that no cartridges should have grease on them, and that sepoys could grease them with whatever they wanted.