The catalyst of the rebellion was the execution of Mangal Pandey, a sepoy who had attacked British officers at the Barrackpore garrison on March 29. The British executed Pandey in early April, inflaming tensions among the sepoys, particularly as the punishment included disbanding Pandey’s regiment and harshly punishing sympathetic soldiers. The situation further deteriorated in April when sepoys at Meerut were imprisoned for refusing to use the new Enfield cartridges, rumored to be greased with cow and pig fat. This led to a revolt on May 10, 1857, when sepoys killed their British officers and captured Meerut. They then marched to Delhi, seeking the support of the Mughal Emperor Bahadur Shah II. By May 11, the rebels had taken control of Delhi, and the aging emperor was reinstated as a figurehead. The capture of Delhi galvanized the rebellion, which rapidly spread through northern and central India. The rebellion drew in various groups dissatisfied with British rule, including landlords, merchants, and peasant farmers from both Hindu and Muslim communities. Despite this broad support, the rebels lacked a unified command and clear objectives, weakening their efforts. While some Indian leaders, such as Queen Rani Lakshmi Bai of Jhansi and Nana Sahib, joined the rebellion, others remained loyal to the British or were ineffective in rallying support. The rebellion saw significant regional variations, with some areas experiencing intense uprisings and others remaining relatively calm. In response, the British launched a multi-pronged military campaign. Initial efforts focused on Delhi, where fierce fighting took place from July to September 1857. The British, using reinforcements and heavy artillery, eventually recaptured the city on September 18, after a brutal siege and street fighting that led to significant destruction and looting. Meanwhile, other major conflicts occurred in Kanpur and Lucknow. At Kanpur, the British forces, led by General Wheeler, faced a protracted siege. A failed evacuation plan led to the Bibighar massacre, which intensified British resolve and led to severe reprisals. In Lucknow, British Commissioner Sir Henry Lawrence initially fortified the Residency but fell early in the siege. The British managed a partial relief of the garrison but faced ongoing attacks. It wasn't until November 1857, when Sir Colin Campbell led a successful relief operation, that the siege was fully lifted. The British forces then regrouped and pushed back against further rebel attempts, including those led by Tantia Tope. The rebellion’s impact was also felt in Jhansi, where the British annexed the state under the doctrine of lapse following the death of the Raja. Rani Lakshmi Bai led significant resistance, capturing Gwalior and defending Jhansi with notable success until her defeat and death at the Battle of Gwalior in June 1858. This marked the end of major organized resistance in the region. In other regions, such as Bihar and Punjab, the rebellion saw localized uprisings that were eventually subdued by British forces. Notable figures like Kunwar Singh in Bihar led effective but ultimately unsuccessful resistance against the British. In the Punjab and Afghan Frontier, isolated uprisings occurred, but British forces, including local Sikh troops, effectively contained them.