Around 1840, the EIC wanted to shift from flintlocks to percussion small-arms.
• Over the next decade, ~460,000 percussion arms were procured.
• Procurement ceased ~June 1851, to shift to utilizing a newer design of rifles, suiting the 'Delvigne-Minié' concept.
• The Board of Ordnance finally settled on The Pattern 1853 Rifled Musket, with a .577 bore.
• This Pattern 1853, was known as the Enfield Rifle.
• The first Enfields reached India in 1853 for tests.
• General Gromm, had warned then Secretary to Military Board, that cartridges for the rifles must not contain any grease, which may offend sepoy's caste sentiments.
• The warnings were ignored & tests were conducted at Kanpur, Rangoon & Fort William over months.
• The cartridges did contain tallow, which may have come from pigs or cows.
• 1855, Bengal Army's Ordnance Department began manufacturing ammunition at Meerut & Dum Dum arsenals.
• The grease for the rifle patch was adapted to contain 5 : 5 : 1, tallow : stearine : wax.
• The nature of tallow wasn't officially specified however.
• Rifle Instruction began in January 1857, at Musketry Depots at Ambala, Sialkot & Dum Dum near Calcutta.
• By late January itself, rumours about the tallow began to spread out of the Dum Dum Depot.
• In February, the first serious outbreak of Mutiny occured, when the 19th Bengal Native Infantry (B.N.I), protested the cartridges.
• A court of inquiry found their grievances unfounded.
• By mid-March, the 41st B.N.I, also mutinied at Ambala, owing to it's disaffection with the cartridges.
• The Mangal Pandey incident, occured in late March, 2 days before the disbandment of the 19th B.N.I, at Barrackpore.
• Mangal Pandey himself was a sepoy of the 34th B.N.I.