The siege of Cawnpore was one of the two great sieges of the Indian Mutiny. (The other was Lucknow.) There was the siege of Delhi, of course, but there it was the British doing the besieging. At Cawnpore, a tiny British force found itself trapped in a totally inadequate defensive position, surrounded by a hugely bigger Indian force, supported with cavalry and artillery. Despite this, they held out from 6th to 25th June 1857, before accepting terms and agreeing to surrender in exchange for safe conduct out of the town.
The Indian forces, under Nana Sahib, reneged on the terms of the surrender and attacked the British as they boarded the boats they had been promised would take them to safety. The massacre (and massacre it was, as almost all the soldiers who had survived the siege were killed at the boats) was bad enough, but terrible things happen in war. It was what came next that made Cawnpore a byword for horror for almost a century and was used to justify appalling acts of retribution by the British after the real fighting in India was over.
The European civilians had taken shelter with the army when mutiny broke out at Cawnpore. The men fought alongside the soldiers and were massacred with them. There were, though, around 375 women and children who were also trapped in the siege. It was concern about the safety of these civilians which was a principal reason for the surrender. Many of the women and children were killed at the boats, but after the initial bloodshed, those who survived were taken prisoner. They were kept in a private house. The house was said to have once belonged to the mistress (or 'bibi') of a British officer, and it was therefore called the Bibighar. Around 180 women and children were imprisoned there.
Conditions in the Bibighar were, to put it mildly, poor, but some effort was made to ensure that the prisoners received food and medical attention. They were even occasionally allowed to take the air outside the house – an important concession in a jam-packed building in the summer heat.
It seems likely that Nana Sahib didn't really know what to do with his prisoners. There were those in his court (notably his adoptive father's widows), who demanded that he show mercy to the women and children. Others, though, had a different agenda. As the British forces sent to relieve Cawnpore drew close to the city, the latter group gained the upper hand.
A little before 5.30 in the evening of 15 July, the women of the Bibighar were told that Nana Sahib "had sent orders for their immediate destruction". The soldiers ordered to do the killing refused, most firing instead into the ceilings.
In the end, five men (two of them butchers) went into the Bibighar with swords and cleavers and set about hacking all those within to death. Their leader hacked with such a combination of enthusiasm and incompetence that he twice broke his sword and had to send out for new ones.
The next morning, the bodies were removed and thrown down a nearby well. It emerged that not all of them were dead, but the wounded were thrown in anyway. Three or four children, who had survived uninjured, ran helplessly around as the bodies were disposed off. Once the adults were all in the well, the children were killed and tossed in after them.
The British arrived the next day, to find the evidence of the atrocity. Thereafter, British forces in India showed no mercy to any men who were or might have been involved in the insurrection. As one officer wrote, "When I am tempted to show mercy, I just think, 'Cawnpore'."