India and Pakistan have fought no fewer than four full-on wars since the two nations came into being in 1947. Where the 1971 war stands out from the others is that it had nothing (directly, at least) to do with the disputed region of Kashmir. In fact, the 1971 Indo-Pakistani War was really the final phase of another conflict, the Bangladesh Liberation War. That war, if you don’t already know, is the reason why Bangladesh is Bangladesh, and not “East Pakistan.” Both wars came to their end on this date in 1971.
The Bangladesh Liberation War had its beginnings in…well, in the formation of Pakistan in the first place. Apart from religion, there was really no justifiable reason that yours truly can figure out for trying to mash Pakistan and Bangladesh together into one state. The two places are completely separated by culture, language, history, and geography, to name just a few things. The only thing apart from Islam that united them was the desire of Indian Muslim leaders to create a nation that was closer to population parity with India than either Pakistan or Bangladesh were individually. As it turns out, that’s not really a solid basis for national unity.
Any chance for a harmonious united Pakistan went out the window shortly after it was founded, when the Speaker of Pakistan’s National Assembly, Muhammad Ali Jinnah, declared that Urdu would be the new nation’s only official language (apart from English, which had official status owing to the British Empire days). That was swell for all the Urdu speakers, but it kind of sucked if you happened to be a Bengali speaker, and at the time the population of East Pakistan was actually greater than the population of West Pakistan (today Pakistan’s population is somewhat larger than Bangladesh’s), so Bengali speakers were actually the majority. On February 21, 1952, known as “Language Martyrs’ Day” in Bangladesh, a number of Bengali students were killed by Pakistani security forces while protesting for Bengali to be made co-equal with Urdu. You could argue that these were the first shots fired in the war, even though it took ~19 years for the subsequent shots to be fired. Bengali eventually was given official status in Pakistan, but getting there caused some irreversible damage to the national fabric.
Language policy wasn’t the only area where West Pakistan exerted its will over East Pakistan. A look at Pakistan’s budget from 1950-1970 shows that only around 40% was spent in the east. The political system was gamed to favor West Pakistan despite the slight population edge in East Pakistan. The vast majority of military spending benefited West Pakistan, and so East Pakistanis were in relatively constant fear of an Indian invasion that they simply wouldn’t have been able to repel. Essentially, West Pakistan treated East Pakistan like its very own colony. Really the only surprising thing about the war is that it took so long before it finally began.
Two 1970 events brought things to a head. First, in November, a massive category 3 tropical cyclone struck all of the Bengal region. Somewhere between 300,000 and 500,000 people died and the storm caused almost $87 million in damage (over $540,000,000 in 2015 dollars). It remains the deadliest tropical cyclone in recorded history, and was (along with the war) one of the motivations for the famous George Harrison and Ravi Shankar-organized “Concert for Bangladesh,” held in August 1971. Pakistan, at the time, was ruled by a military junta led by West Pakistani General Yahya Khan (d. 1980), who managed to make the death toll worse by completely botching the relief and recovery effort. This was probably just plain incompetence, but for Bengalis who had been getting the short end of the stick from West Pakistan for more than two decades, the response just confirmed that East Pakistan wasn’t getting a fair shake.
In December, Khan’s junta held parliamentary elections. Fed-up East Pakistanis voted en masse for the largest East Pakistani political party, the Awami League, which thereby won a national majority without winning a single West Pakistani seat. Now, East Pakistani politicians had been named Prime Minister a couple of times since independence, but each time they wound up being maneuvered out of office by West Pakistani leaders. This time, the leader of West Pakistan’s Pakistan People’s Party, Zulfikar Ali Bhutto (d. 1979), simply rejected the idea that the Awami League’s leader, Sheikh Mujibur Rahman (d. 1975), could become PM. He proposed, as a lame “concession,” that maybe there could be two PMs, one for each half of the country. East Pakistanis were not assuaged.
Rahman called for a national strike, and demonstrators took to the streets throughout East Pakistan. In March, the Pakistani military just happened to send a troop and ammo transport ship to dock at Chittagong, East Pakistan’s main port city. It also began infiltrating West Pakistani soldiers into East Pakistan on a series of hurriedly-scheduled “civilian flights” from the west. East Pakistani military units began to refuse orders to fire on demonstrators, choosing to mutiny rather than obey orders from West Pakistani officers to fire on their fellow Bengalis.
On March 25, 1971, the Pakstani military began “Operation Searchlight,” an attempt to pacify the Bengalis by, uhhh, killing a whole bunch of them. On March 26, not coincidentally, Rahman sent a declaration of Bangladesh’s independence to Awami League figures in Chittagong (he was arrested by Pakistani forces not long after). The atrocities that followed are frequently labeled, collectively, as a genocide. Pakistani forces seized cities to quash political opposition and formed paramilitary brigades of Pakistani sympathizers (some Bengalis but also Pakistani migrants), which committed most of the worst crimes. Estimates vary widely, but the largest ones claim that as many as 3 million Bangladeshis were killed (more conservative estimates suggest 1.5 million or less, and the most conservative estimate only around 25,000-50,000), and another 200,000-400,000 Bangladeshi women were raped. Millions of Hindus in Bangladesh fled as refugees across the border into India.
The harder Pakistan cracked down, the stronger the Bangladeshi people’s will to resist them became. An army was quickly put together and adopted a Fabian strategy, whereby regular Bangladeshi military units would focus on holding territory (to make the case for Bangladeshi nationhood to the international community), but most of the fighting would be undertaken by guerrilla units (the Mukti Bahini or “freedom fighters”) conducting quick strike attacks against the Pakistanis and against any infrastructure that was being used by the Pakistanis. Pakistani ships in Bangladeshi ports were targeted with mines. None of this was decisive, but it wasn’t really meant to be. The Bangladeshi war aim was simply survival, and in that sense their strategy was very effective.
The decisive blow came, as you no doubt guessed from the opening paragraph, from India, which entered the war (or, depending on your perspective, started another war) on December 3. Technically they were brought into the war, after the Pakistani air force pre-emptively struck 11 Indian air bases, but in reality India was already arming and training the Mukti Bahini and was on the verge of directly intervening anyway. Aside from the general enmity that existed between India and Pakistan, mostly over Kashmir, India was planning to intervene because Indian Prime Minister Indira Gandhi’s (d. 1984) government had determined that it would be cheaper to get involved in the war directly than to continue absorbing the millions of refugees that Pakistani atrocities were sending over the border.
When I say that the Indian intervention was decisive, I mean decisive. It took all of 13 days from their entry into the war to Pakistan’s surrender. India quickly established air and naval dominance over and around Bangladesh, and it then sent in a ground force that was large enough to simply overwhelm the Pakistanis, who had been fighting small skirmishes with the Mukti Bahini and were totally unprepared to withstand a massive assault by a large army. In the west, India launched a series of airstrikes inside Pakistan and engaged in mostly defensive ground action along the India-Pakistan border. Indian forces did take some Pakistani territory, but they eventually gave it back in the negotiations that followed the war.
The Pakistani commander in Bangladesh, whose position was untenable, surrendered on December 16, 1971, ending two wars in one fell swoop. The United States sent a naval task force, including the aircraft carrier USS Enterprise into the Bay of Bengal, so as to dissuade India from taking any more offensive action against Pakistan, and this briefly raised the threat of a Cold War-related escalation, as the USSR sent its own ships into the bay to shadow the Americans. Luckily nothing came of this.
Bangladesh was now independent, although it took almost three years before it finally gained universal recognition (including from Pakistan) and was admitted to the UN (China, Pakistan’s close ally, had vetoed Bangladesh’s previous bids for admittance). Sheikh Mujibur Rahman became Bangladesh’s first president on January 12, 1972, and later served as its prime minister. His counterpart, Yahya Khan, didn’t fare so well–protests against his failure broke out all over Pakistan, and he handed the presidency over to Bhutto on December 20. Bhutto, who later contended that the whole affair was simply a “tragic civil war” that the terrible Indians had to go and blow all out of proportion, ordered work to begin on a covert Pakistani nuclear weapons program, thinking that a Pakistani nuke would give it a pretty strong deterrent against future Indian military action. Pakistani intelligence services, meanwhile, began supporting jihadi groups in Kashmir and Afghanistan, thinking that if push ever came to shove these would be valuable forces to bring to bear against the Indian army. I think we can all agree that this plan has worked out really well for everybody.