The rebellion's immediate trigger was absurdly specific: a new rifle cartridge, the Pattern 1853 Enfield, whose paper wrapping was rumored to be greased with cow and pig fat. Loading the weapon required biting the cartridge open, an act that would defile both Hindu and Muslim soldiers. The East India Company dismissed the concern. The sepoys did not. On 9 May 1857, eighty-five men of the 3rd Bengal Cavalry at Meerut, 43 miles northeast of Delhi, refused the cartridges and were court-martialled, shackled in irons, and paraded before the garrison as a warning. The warning worked -- just not as intended. The following evening, soldiers of three Bengal regiments broke into open revolt, freed the prisoners, killed their British officers, and marched through the night toward Delhi. The senior Company officers at Meerut, stunned despite months of warning signs from other garrisons, did nothing to pursue them.

Delhi in 1857 was a city living on its past. The Mughal Empire, which had once commanded most of the subcontinent, had been reduced to a pensioned title and a crumbling court. Bahadur Shah II, the emperor, was elderly and had been told by the Company that the Mughal title would die with him. There were no European troops stationed in the city -- only three Bengal Native Infantry regiments whose loyalties were already fraying. When the Meerut rebels arrived on 11 May, Delhi's own sepoys joined them. Company officers and civilians who tried to shelter in the Main Guard near the Kashmiri Gate were killed. By nightfall the rebels controlled the city and had declared Bahadur Shah the leader of their uprising. He accepted reluctantly, lending the rebellion a national symbol it desperately needed but strategic coordination it would never quite achieve.

British reinforcements arrived piecemeal and took position on a rocky ridge two miles north of the city walls, where they found themselves besieging a force that outnumbered them several times over. Through June, July, and August of 1857, the ridge camp became a furnace of cholera, heat exhaustion, and constant rebel sorties. The commanding general, Anson, died of cholera at Karnal before even reaching Delhi. His successor pushed forward and won the Battle of Badli-ki-Serai on 8 June, clearing a position on the ridge, but lacked the numbers to assault the city. The Corps of Guides, marching hundreds of miles through the hottest season -- which also coincided with Ramadan, meaning their Muslim soldiers could neither eat nor drink during daylight hours -- arrived and went into action almost immediately. Reinforcements trickled in from the Punjab, including Sikh, Punjabi, and Gurkha regiments whose willingness to fight against the Bengal sepoys would prove decisive.

The siege broke open in September. Brigadier John Nicholson arrived on 14 August with a flying column of 4,200 men, and on 25 August routed a rebel force at the Battle of Najafgarh despite monsoon flooding that turned roads into rivers. When the siege train finally reached the ridge in early September -- six 24-pounders, eight 18-pounder guns, six 8-inch howitzers, four 10-inch mortars, and nearly 600 ammunition carts -- the bombardment began. Batteries were placed within 700 yards of the walls, and over several days the guns tore breaches near the Kashmiri Gate and the Water Bastion. On 14 September, five assault columns surged through the breaches. The fighting inside the city was savage, block by block, lasting nearly a week. Nicholson himself was mortally wounded leading the first column. By the time the last pockets of resistance fell, the British force of roughly 9,000 had taken a city defended by tens of thousands.

Bahadur Shah II was captured hiding in the tomb of his ancestor Humayun, south of the city. He was tried and convicted on several charges, then exiled to Rangoon in British-controlled Burma, where he died in 1862 -- the last Mughal emperor, ending a dynasty that had ruled for over three centuries. The fall of Delhi shattered the rebellion's symbolic center. Without a figurehead or a capital, the remaining rebel forces across northern India lost cohesion and were defeated in detail over the following months. Twenty-nine Victoria Crosses were awarded for bravery during the siege. The cost in Indian lives -- soldiers, civilians, those caught between two empires -- was far greater and far less precisely counted. Within a year, the East India Company's rule was dissolved and replaced by direct British Crown governance, inaugurating the British Raj. The rebellion that the British called a mutiny, and that Indians would later call the First War of Independence, had remade the subcontinent's political order at the walls of Delhi.