Three weeks later, the 3rd Light Cavalry openly refused orders, and fighting soon spread from Meerut, with the greatest violence coming at Cawnpore and the siege of Lucknow.  
Its official beginning was the attempted murder and subsequent suicide committed by Mangel Pande, whose unit was disbanded by General Hearshey as a result.  Three weeks later, the 3rd Light Cavalry openly refused orders, and fighting soon spread from Meerut, with the greatest violence coming at Cawnpore and the siege of Lucknow.  The arrival of reinforcements under Colin Campbell led to its eventual end in 1859.  Catalyzed by the use of beef and pork fat in Enfield rifle cartridges, FTP, name this 19th-century rebellion against the British in northern India.
Its official beginning was the attempted murder and subsequent suicide committed by Mangel Pande, whose unit was disbanded by General Hearshey as a result.  
Sepoy Mutiny or Rebellion (prompt on "Bengal Mutiny")