When the British finally departed the Indian subcontinent on 15 August 1947, after nearly 200 years of colonial rule, they left a jigsaw legacy — the vast country of India flanked on either side by the new country of Pakistan split in two parts. As we reach the 70th anniversary of partition, relations between the two nations are as broken as ever. In some ways, their violent birth pangs dictated their future course through suspicion and animosity.

India Pakistan tension
India Pakistan tension
India Pakistan tension
India Pakistan tension
India Pakistan tension

The territory of East Pakistan broke away to become independent Bangladesh in 1971 after a war between Bangladeshi nationalists, backed by India, and Pakistani forces. About three million people were killed in the conflict.

India Pakistan tension
24 July 1971: A Unicef jeep in seen on the destroyed streets of Madhabpur during the Indo-Pakistani War of 1971. This war in which East Pakistan and India fought against West Pakistan resulted in the secession of East Pakistan, becoming the independent nation of BangladeshAFP
India Pakistan tension
1971: Mukti Bahini guerrilla fighters at the race track in Dhaka prepare to bayonet men who reportedly collaborated with the Pakistani army during East Pakistan's fight to become the independent state of BangladeshWilliam Lovelace/Getty Images
India Pakistan tension
26 July 1971: Refugees from East Pakistan shelter in concrete sewage pipes near the Salt Lake camp in CalcuttaKeystone/Getty Images
India Pakistan tension
21 September 1971: An emaciated Bangladeshi refugee in Salt Lake camp in CalcuttaKeystone/Getty Images
India Pakistan tension
11 November 1971: A young boy receives a vaccination against the cholera epidemic that arose in the wake of a devastating cyclone in the Orissa area of East Pakistan (Bangladesh). The cyclone claimed thousands of lives and threatened survivors with starvation and diseaseCentral Press/Getty Images
India Pakistan tension
11 December 1971: Indian army officers and soldiers stand on a captured Pakistani tank in the desert in the state of Rajasthan during the India-Pakistan border conflictAFP
India Pakistan tension
17 December 1971: An elderly Pakistani refugee is pushed aside by Indian troops advancing into the East Pakistan (which later became Bangladesh)Central Press/Getty Images
India Pakistan tension
22 December 1971: Mukti Bahini (Bangladeshi liberation force) troops head to the front line in East Pakistan during the India-Pakistan conflict when India supported East Pakistan's struggle to become the independent state of BangladeshWilliam Lovelace/Getty Images
India Pakistan tension
22 December 1971: A bridge blown up on the Jessore Road during the conflict in which India supported East Pakistan's struggle to become the independent state of BangladeshExpress/Express/Getty Images
India Pakistan tension
23 November 1971: An elderly woman comforts her malnourished grandchildren in a field hospital in Calcutta, having fled from East Pakistan to avoid the civil war and the cyclonesCentral Press/Getty Images
India Pakistan tension
December 1971: A group of Indian soldiers captured by the Pakistani army pose for a photographer in a POW campAFP
India Pakistan tension
Sheikh Mujibur Rahman, the founding leader of Bangladesh. He became the first President of Bangladesh (formerly East Pakistan) Ian Brodie/Daily Express/Hulton Archive/Getty Images
India Pakistan tension
16 December 1971: Bangladeshi army tanks take part in a ceremonial parade in Dhaka after the country won independence from Pakistan following a nine-month warReuters

India was the first to conduct a nuclear test, in 1974. India didn't conduct nuclear tests again until 1998. Pakistan followed with its own nuclear tests just a few weeks later. Experts say the two sides have since armed themselves with hundreds of nuclear warheads as well as missile delivery systems.

India Pakistan tension
18 May 1974: A crater marks the site of the first Indian underground nuclear test conducted at Pokhran in the desert state of RajasthanAFP
India Pakistan tension
30 June 1988: An armed security official stands guard near the hill under which Pakistans five nuclear tests were carried out, situated in southwestern Baluchistan province. Pakistan conducted six nuclear tests on 28 and 30 May in response to India's second nuclear tests on 11 and 13 MaySaeed Khan/AFP
India Pakistan tension
23 March 2001: A military truck transports the Shaheen II, a surface-to-surface missile with a range of 2,300 km (1,430 miles), during a military parade in Islamabad. President Mohammad Rafiq Tarar said that Pakistan had become the world's seventh and the Muslim world's first nuclear power, but that the country wanted a peaceful settlement to its 53-year-old dispute with India over KashmirReuters
India Pakistan tension
26 January 2002: An Indian military truck displaying an Agni II ballistic missile passes by the India gate in New Delhi. The short-range version of the nuclear-capable Agni I missile was tested successfully, which prompted angry condemnation from rival PakistanAFP

No issue has bedevilled India-Pakistan relations like the disputed Himalayan region of Kashmir. Soon after gaining independence, both sides claimed the majority-Muslim region in its entirety. Kashmir's Hindu ruler wanted to stay independent, but local uprisings and a raid by Pakistani tribesmen drove the maharaja to seek assistance from Indian troops.

This spiralled into a yearlong war that ended with a UN-brokered ceasefire and Kashmir divided by the heavily militarised Line of Control, which splits the region into two areas, one administered by India, one by Pakistan.

India Pakistan tension
27 December 2001: Indian Border Security Force troops patrol along the Line of Control that divides Indian and Pakistani KashmirTauseef Mustafa/AFP
India Pakistan tension
21 August 2011: The India-Pakistan border appears as an orange line in this photograph taken by a crew member on the International Space Station. The fence between the two countries is floodlit for surveillance purposes. Srinagar (L), Islamabad (bottom C), Lahore (centre) and Delhi (top C) can be seen as brighter spotsNasa/Reuters

Kashmiri discontent with Indian rule took root as successive governments reneged on a promise to allow a referendum. India and Pakistan fought a second war over Kashmir in 1965 that resulted in little change.

India Pakistan tension
1965: A disabled Pakistani tank lies by the roadside in the Bahara sector during the India-Pakistan conflictKeystone/Getty Images
India Pakistan tension
23 September 1965: Army general J N Chaudhuri and Air Marshal Arjan Singh look at a map at the Defence Headquarters in New Delhi after the ceasefire in the Indo-Pakistan warKeystone/Getty Images

When a full-blown rebellion erupted in 1989, India deployed even more troops to the region. Thousands of Kashmiri fighters staged bloody attacks on Indian security forces and on pro-India Kashmiri politicians. In 1999 the two were involved in a battle along the Line of Control that some analysts called an undeclared war. Their forces exchanged gunfire over a ceasefire line for years until a truce in late 2003 paved the way for peace talks.

India Pakistan tension
28 May 1999: Pakistani army soldiers inspect the wreckage of an Indian Air Force fighter plane at an undisclosed site in the Pakistan-ruled part of Kashmir. The plane was one of the two shot down by the Pakistani armyReuters
India Pakistan tension
31 May 1999: Indian soldiers fire 105mm guns from their outpost near Kargil towards the India-Pakistan border in KashmirArko Datta/AFP
India Pakistan tension
14 June 1999: A displaced Kashmiri mother tries to comfort her child while sitting outside their camp in Baghicha Thung village near the ceasefire line with Indian-controlled Kashmir. More than 60,000 have been reported displaced in the Pakistan-ruled part of Kashmir after the escalation of clashes between India and PakistanReuters
India Pakistan tension
22 June 1999: A convoy of trucks loaded with arms and munitions for Indian Army soldiers make their way up a mountain at Zojila as the foes exchange heavy artillery fire across the disputed Kashmir borderReuters
India Pakistan tension
15 July 1999: Indian soldiers hold aloft a national flag at Point 4875, one of the peaks they captured from 'guerrilla infiltrators' in the Drass sector of Kashmir. Islamabad denied Indian claims that most of the guerrillas were its soldiers, but later acted under international pressure to influence the guerrillas to withdrawReuters
India Pakistan tension
22 July 1999: Indian defence minister George Fernandes takes aim through a shoulder-held grenade launcher which was reportedly confiscated from Muslim infiltrators in Kargil. Fernandes said that there could be no talks between India and Pakistan regarding the Line of Control until all 'infiltrators' withdraw from Indian territory and shelling from across the border comes to a haltArko Datta/AFP
India Pakistan tension
22 October 2001: Indian soldiers look out from a bunker pockmarked with bullet holes after an attack outside an Indian military airfield at Quil, near Srinagar in Kashmir. Indian airforce authorities said that six people including four separatist militants were killed when militants tried to storm their military airfield. Lashkar-e-Taiba, a Pakistan based militant organisation, claimed responsibility for the attackReuters
India Pakistan tension
30 December 2001: Indian soldiers sit on a roadside near Naushera, west of Jammu. India and Pakistan massed troops along their borders in the biggest such build-up in 15 years following the attack on the Indian parliamentReuters
India Pakistan tension
29 May 2002: Three-year-old Indian refugee Ashu Sharma looks through a mesh door at a camp in Samba sector, some 40km (25 miles) from Jammu. Thousands of Indian villagers left their homes along the India-Pakistan border, fearing a fourth war between the two countriesArko Datta/Reuters
India Pakistan tension
24 September 2002: Indian Border Security Force troopers storm a building in Srinagar to flush out Muslim separatists holed up inside, ending a night-long siegePawel Kopczynski/Reuters
India Pakistan tension
8 October 2002: Three blindfolded suspects are held in police custody in Rawalpindi, Pakistan. Police said the three accused, all residents of Indian-ruled Kashmir, were members of the Indian intelligence agency sent to sabotage parliamentary electionsMian Khursheed/Reuters
India Pakistan tension
26 November 2003: Pakistani soldier Sher Jamal Khan and Indian soldier DK Sharma exchange gifts to mark Eid al-Fitr at the India-Pakistan Wagah border crossing after India and Pakistan began a ceasefire along their frontier in KashmirMunish Sharma/Reuters
India Pakistan tension
15 January 2004: A Pakistani ranger and a policeman stand guard in front of the Samjhota Express at the Wagah border railway station as rail links resume after a two-year gapArif Ali/AFP
India Pakistan tension
11 March 2004: A man waves the flag of Pakistan at the Wagah border crossing between Pakistan and India as the Indian cricket team were beginning their first full tour of Pakistan in almost 15 yearsScott Barbour/Getty Images
India Pakistan tension
21 October 2008: Pakistani rangers open the gate at a crossing point on the military ceasefire line or Line of Control at Chakka-da-Bagh, about 250km (155 miles) northwest of Jammu. Trucks crossed the frontier in divided Kashmir for the first time in decades as India and Pakistan opened the trade link, aimed at easing tensionAmit Gupta/Reuters

The Line of Control ends abruptly at Siachen Glacier, a 6,100-metre-high (20,000ft) icy Himalayan expanse that is the world's highest battlefield. Thousands of troops have been deployed on the glacier since 1984, laying claim to territory so hostile to human life it has never been demarcated. Far more troops have died from avalanches or bitter cold than in combat. While there are no clear borders on the glacier, its position between the Indian and Pakistani-controlled portions of Kashmir makes it a key part of any final map that may be drawn of the region. Its high altitude gives its occupants an advantage over those below.

India Pakistan tensions
29 June 1999: Pakistan soldiers, tied to each other for safety in hostile weather conditions, carry their weapons across the Siachen Glacier, the world's highest battlefieldReuters

Kashmir has been relatively quiet over the last decade or so, and most anti-India sentiment is expressed in regular street protests by tens of thousands of civilians. They are sometimes quelled by deadly force.

In 2016, however, there were several major security incidents in the region. Six gunmen attacked an Indian air force base in the northern town of Pathankot in January, killing seven soldiers in a battle that lasted nearly four days. In July, Indian soldiers killed Kashmiri rebel leader Burhan Wani, sparking months of anti-India protests and deadly clashes in the region. Two months later, suspected rebels infiltrated an Indian army base in Kashmir and killed 18 soldiers. Four attackers were also killed.

India Pakistan tension
28 January 2015: Kashmiri people gather around the body of a militant, who was killed by Indian soldiers, during his funeral in Handoora, south of Srinagar. An Indian army colonel was among four people killed in a gun battle, the highest ranking military officer to die in fighting in the disputed Himalayan region in more than a yearDanish Ismail/Reuters
India Pakistan tension
20 March 2015: The mother of an Indian policeman who was killed in an attack on a police camp, weeps at her residence in Kathua district, south of Jammu. Militants stormed a police camp in Indian Kashmir, killing two policeman and wounding three, a police official said, ending a three-month lull in attacksMukesh Gupta/Reuters
India Pakistan tension
15 August 2016: Indian army troops take position inside a building after a gunfight in Srinagar. A police paramilitary commander was shot dead in Kashmir's main city while at least two suspected separatist militants were killed in gun battles as violence flared in the disputed Himalayan region on Independence DayTauseef Mustafa/AFP
India Pakistan tension
16 August 2016: Kashmiri mourners look on during the funeral of four civilians at Aripanthan Magam village in Budgam district on the outskirts of Srinagar. Authorities imposed a curfew in large parts of Kashmir, during an upsurge in violence sparked by the killing of a top militant commander called Burhan Wani in a gun fight with security forcesTauseef Mustafa/AFP
India Pakistan tension
11 October 2016: Indian paramilitary troopers look towards a building where suspected militants were thought to be hiding, on the second day of a gun fight between the army and suspected militants in Pampore, south of SrinagarTauseef Mustafa/AFP
India Pakistan tension
4 November 2016: An Indian policeman aims his gun during a protest in Srinagar in Indian-administered KashmirDanish Ismail/Reuters
India Pakistan tension
29 March 2017: People react as they sit in a window of a mosque during the funeral of Tauseef Ahmad Wagay, a suspected militant who was killed in a gun battle with the Indian army in Chadoora, in Yaripora, in south Kashmir's Kulgam districtDanish Ismail/Reuters

Pakistan-based militants have launched attacks within India, hitting its seat of government and its financial powerhouse. In December 2001 gunmen attacked India's Parliament, killing 14. India blamed militant groups Lashkar-e-Taiba and Jaish-e-Muhammad, and deployed troops to its western frontier with Pakistan. The standoff ended in October 2002 after international mediation.

India Pakistan tension
13 December 2001: Police take up position outside Parliament in New Delhi after suspected militants launched a daring assault on the Indian parliament, triggering a shoot out with security forcesRaveendran/AFP

On 26 November 2008, ten militants arrived on the Mumbai shoreline in a dinghy, before splitting into four groups and embarking on a spree of bloodletting that left 166 people dead. They held off elite commandos for up to 60 hours in two luxury hotels and a Jewish centre in the city.

Nearly four years later, India secretly hanged the lone survivor of the Pakistan-based militant squad responsible for the rampage through Mumbai.

India Pakistan tension
29 November 2008: Smoke and flames billow out from the Taj Mahal hotel in Mumbai during four days of coordinated attacks by militants from the Lashkar-e-Taiba Islamic militant organisation based in Pakistan that left 164 people deadSajjad Hussain/AFP
India Pakistan tension
26 November 2008: An employee of the Taj Mahal hotel is helped by a colleague after jumping out from a higher floor of the hotel, site of one of several coordinated attacks by Islamist militants in MumbaiLorenzo Tugnoli/AFP
India Pakistan tension
21 November 2012: Indian sand artist Sudarsan Pattnaik finishes his sand sculpture of Mumbai gunman Mohammed Kasab at Talasari beach in Balasore district in the state of Orissa, following news of his execution. The sole surviving gunman from the 2008 Mumbai attacks was executed to the relief of survivors and victims' families, nearly four years after 166 people died in the three-day rampageAFP

The many efforts to resolve the longstanding disputes between India and Pakistan have all, so far, been in vain. In 2014, Indian Prime Minister Narendra Modi began his term on a conciliatory note by inviting his Pakistani counterpart, again Nawaz Sharif, to his oath-taking ceremony and paid a surprise visit to Sharif's home in Lahore the following year.

But the friendliness dissolved days later when gunmen, allegedly from Pakistan, killed seven soldiers at an Indian air force base. Months later, Modi ordered a surgical strike on alleged insurgents inside Pakistani-controlled Kashmir, and vowed to isolate Islamabad diplomatically.

India accuses Pakistan of sponsoring terrorism, a charge Pakistan denies. Peace talks are unlikely to resume any time soon.