Refusing to "bite the cartridge" was a turn of phrase used by the British in India of Native Indian solidiers (sepoys) who had mutinied in 1857. A sepoy (from Persian سپاهی Sepâhi meaning soldier) was a native of India employed as a soldier in the service of a European power, usually of the United Kingdom. ... 1857 was a common year starting on Thursday (see link for calendar). ...

It derives from the act of biting open a paper cartridge containing gunpowder in order to load contemporary rifles. Gunpowder whether black powder or smokeless powder, is a substance which burns very rapidly and is used as a propellant in firearms. ... A rifle is any long gun which has a rifled barrel. ...

One of the alleged causes of the Indian Mutiny were rumours that the grease on these cartridges designed to keep them dry was, variously, pork or beef fat (pork being abhorrent to Muslims, beef to Hindus), thus their refusal to bite them. An engraving titled Sepoy Indian troops dividing the spoils after their mutiny against British rule gives a contemporary view of events from the British perspective. ... A Muslim (Arabic: مسلم) (sometimes also spelled Moslem) is an adherent of Islam. ... A Hindu (also spelt Hindoo) is an adherent of philosophies and scriptures of Hindu religion. ...

This phrase, alternately expressed as "biting the bullet" is used to refer to an action that is abhorrent to oneself.