By 1845 the British had moved 32,000 troops to the Sutlej frontier, to secure their northernmost possessions against the succession struggles in the Punjab. In late 1845, British and Sikh troops engaged near Ferozepur, beginning the First Anglo-Sikh War. The war ended the following year, and the territory between the Sutlej and the Beas was ceded to Great Britain, along with Kashmir, which was sold to Gulab Singh of Jammu, who ruled Kashmir as a British vassal.
As a condition of the peace treaty, some British troops, along with a resident political agent and other officials, were left in the Punjab to oversee the regency of Maharaja Dhalip Singh, a minor. The Sikh army was reduced greatly in size. In 1848, out-of-work Sikh troops in Multan revolted, and a British official was killed. Within a few months, the unrest had spread throughout the Punjab, and British troops once again invaded. The British prevailed in the Second Anglo-Sikh War, and under the Treaty of Lahore in 1849, the Punjab was annexed by the British East India Company, and Dhalip Singh was pensioned off. The Punjab became a province of British India, although a number of small states, most notably Patiala, retained local rulers who recognized British sovereignty.
In every way, the Punjab was one of Great Britain's most important assets in colonial India. Its political and geographic predominance gave Britain a base from which to project its power over more than 500 princely states that made up India. Lahore was a center of learning and culture under British rule, and Rawalpindi became an important Army installation.
The Jallianwala Bagh Massacre of 1919 occurred in Amritsar. In 1930, the Indian National Congress proclaimed independence from Lahore. The 1940 Lahore Resolution of the Muslim League to work for Pakistan, made Punjab the centerstage of a different, bloodier and dirtier struggle.
In 1946, massive communal tensions and violence erupted between the majority Muslims of Punjab, and the Hindu and Sikh minorities. The Muslim League attacked the government of Unionist Punjabi Muslims, Sikh Akalis and the Congress, and led to its downfall. Unwilling to be cowed down, Sikhs and Hindus counter-attacked and the resulting bloodshed left the province in great disorder. Both Congress and League leaders agreed to partition Punjab upon religious lines, a precursor to the wider partition of the country.
The British Punjab province, which includes present-day Punjab province of Pakistan, and the Indian states of Punjab, was partitioned in 1947 prior to the independence of Pakistan and subsequently, India. In India, the Panjab province was further partitioned into and forming Haryana, and Himachal Pradesh.