Source:  https://www.quora.com/What-is-the-real-story-behind-the-Operation-Blue-Star

1. Promises Broken
When  the Constitution Act of India was declared in 1950, it declared Sikhism to be “a sect of Hinduism” and offered no safeguards to the Sikh  community. Both Sikh members of the Constituent Assembly refused to sign  the document. They declared vehemently that: “The Sikhs do not accept  this Constitution. The Sikhs reject this Constitution Act.”
Before Independence congress leaders used to promise “Let  God be the witness of the bond that binds me and the Congress to you.  Our Sikhs friends have no reason to fear that it would betray them. For,  the moment it does so, the Congress would not only thereby seal its own  doom but that of the country too. Moreover, the Sikhs are brave people.  They know how to safeguard their rights, by the exercise of arms, with  perfect justification before God and man, if it should ever come to  that” (Young India 19 March 1931) “No  Constitution would be acceptable to the Congress which did not satisfy  the Sikhs.” (Collected works of M K Gandhi Vol.58. p. 192) “The brave  Sikhs of Panjab are entitled to special consideration. I see nothing  wrong in an area and a set up in the North wherein the Sikhs can also  experience the glow of freedom. (Jawaharlal Nehru, Congress meeting:  Calcutta – July, 1944) ”

In  subsequent years, all the personal laws of the Sikhs were abolished and  replaced by Hindu statutes, such as the “Hindu Marriage Act 1955,” the  “Hindu Succession Act 1956,” etc.
When  in 1954 Jawaharlal Nehru was reminded of the solemn promises made to  Sikhs and other minorities by the Hindu-dominated Congress party, he  replied, “The circumstances have now changed.”
2. Linguistic states and Punjabi suba
In  December 1953, Prime Minister Jawaharlal Nehru appointed the States  Reorganisation Commission to prepare for the creation of states on  linguistic lines , Maharashtra based on Marathi ,Gujarat based on  Guajarati but no state of Punjabi was to be formed /reorganised based on  the Punjabi as its language .This led to widespread discontentment  among the Sikhs and Punjabis .During this time J L Nehru asked Hukam  Singh speaker of Lok Sabha if he supports the concept of linguistic  states .To this he replied that he does not support the concept of  linguistic states but if you go for creating linguistic states based on  other languages then I will support the creation of a state based on  Punjabi .
While other linguistic  states were formed in 1956 But Punjabis succeeded in getting Punjab  state which is at times referred to as Lagda or lame Punjab as the one  –third Punjab left after partition of 1947 was further trifurcated into  Haryana , Himachal and present day Punjab on 1 novemeber 1966 .The main  reason for this was threatening present day Hindus living in Haryana  that they will not be treated equally in Punjabi speaking Punjab .So  when plebiscite for creation of new state was conducted most of the  Punjabi speaking Hindus of present day Haryana and Himachal wrote their  mother tongue as Hindi and not Punjabi . After this ill-conceived  campaign of threatening Punjabi Hindus which was spearheaded by Hind  Samachar group of Jalandhar many Punjabi speaking districts like  Ganganagar , Ambala , Karnal were kept out of Punjab and Chandigarh  which was constructed on land taken from Punjabi farmers was declared as  joint capital /UT.
The Akal Takht  played a vital role in organizing Sikhs to campaign for the Punjabi  suba. During the course of the campaign, twelve thousand Sikhs were  arrested for their peaceful demonstrations in 1955 and twenty-six  thousand in 1960-61.
Again on September  1, 1965 when Pakistani forces crossed the international border at  Chhamb Jaurian in Jammu and Kashmir ,the akali leaders immediately  declared their unconditional support to the government .Once again Sikh  soldiers crossed swords with the Pakistanis and Sikh peasantry rallied  to the support of their fighting forces carrying food and help to the  battle front .In 22 days war, the most distinguished record of bravery  was set by Sikh officer Lt General Harbakhsh Singh who had the sole  credit of halting the Pakistani tanks.
At  one time during 1965 war there was panic at Army Headquarters that  Pakistan might break through Indian defences. Harbakhsh Singh’s finest  moment came when the Army Chief, General Choudhary, ordered him “to  abandon Amritsar and set-up a defence line behind the river Beas.”  Rightly, General Harbakhsh Singh refused to follow such an order, and  the threat to Amritsar never developed.
This makes one thing clear Sikhs were not against unity and sovereignty of India but against the denial of their just demands.
3. River waters dispute
Punjab  has the exclusive right to Punjab river waters on the basis of riparian  law. The other states to which these waters have been distributed are  non-riparian, having no valid claim to it. The riparian law is based  upon justice and equity, having international acceptance. It has been  approved by United Nations. In India it has been followed in all other  states and Punjab has been made the only exception
Read more: UNP -river-waters-unlawful-and-unjust-distributions-77338/#ixzz1XYMl6UHv
The  1976 distribution of Punjab river waters, was award of Prime minister  Indira Gandhi vide which Rajasthan was allocated 8.6 maf, Haryana 3.5  maf, Delhi 0.2 maf and Punjab 3.5 maf out of 15.8 maf which was declared  as surplus, though there was no surplus water and this entire water was  much less than the needs of Punjab .
The  central government—against the provisions of the Indian constitution  introduced sections 78 to 80 in the Punjab Reorganisation Act, 1966,  under which the central government “assumed the powers of control,  maintenance, distribution and development of the waters and the hydel  power of the Punjab rivers. It must be remembered here that as per  Indian constitution river water distribution falls under the state list .  Many Sikhs perceived this division as unfair and as an anti-Sikh  measure, since the vast majority of the people of Punjab are dependent  on agriculture.
4. Akali Dal’s demands
The  Akali Dal led a series of peaceful mass demonstrations to present its  grievances to the central government. The demands of the Akali Dal were  based on the Anandpur Sahib Resolution, which was adopted by the party  in October 1973 to raise specific political, economic and social issues.  The major motivation behind the resolution was the safeguarding of the  Sikh identity by securing a state structure that was decentralised, with  non-interference from the central government. The Resolution outlines  seven objectives.
1. The transfer of the federally administered city of Chandigarh to Punjab .
2. The transfer of Punjabi speaking and contiguous areas to Punjab .
3. Decentralisation of states under the existing constitution, limiting the central government’s role.
4.  The call for land reforms and industrialisation of Punjab , along with  safeguarding the rights of the weaker sections of the population.
5. The enactment of an all-India gurdwara (Sikh house of worship) act.
6. Protection for minorities residing outside Punjab , but within India.
7. Revision of government’s recruitment quota restricting the number of Sikhs in armed forces.
The Wall Street Journal noted:
“The  Akali Dal is in the hands of moderate and sensible leadership…but  giving anyone a fair share of power is unthinkable politics of Mrs.  Gandhi [the then Prime Minister of India]…Many Hindus in Punjab  privately concede that there isn’t much wrong with these demands. But  every time the ball goes to the Congress court, it is kicked out one way  or another because Mrs. Gandhi considers it a good electoral  calculation.
5. Emergency and role of Sikhs :
Shortly  after the declaration of the Emergency, the Sikh leadership convened  meetings in Amritsar where they resolved to oppose the “fascist tendency  of the Congress”. The first mass protest in the country, known as the  “Campaign to Save Democracy” was organized by the Akali Dal and launched  in Amritsar, 9 July. A statement to the press recalled the historic  Sikh struggle for freedom under the Mughals, then under the British, and  voiced concern that what had been fought for and achieved was being  lost. The police were out in force for the demonstration and arrested  all those who raised the Sikh call of “Jo Bole So Nihaal, Sat Sri Akal”  (Whoever speaks, shall be fulfilled, Truth is Undying), including the  Shiromani Akali Dal and Shiromani Gurdwara Prabandhak Committee (SGPC)  leaders.
The Prime Minister seemed  genuinely surprised at the strength of the response from the Sikhs.  Fearing their defiance might inspire civil disobedience in other parts  of the county, she offered to negotiate a deal with the Shiromani Akal  Dal that would give it joint control of the Punjab Legislative Assembly.  The leader of the protests, Sant Harcharan Singh Longowal refused to  meet with government representatives so long as the Emergency was in  effect. In a press interview, he made clear the grounds of the Save  Democracy campaign.
“The question  before us is not whether Indira Gandhi should continue to be prime  minister or not. The point is whether democracy in this country is to  survive or not. The democratic structure stands on three pillars, namely  a strong opposition, independent judiciary and free press. Emergency  has destroyed all these essentials.”
While  the civil disobedience campaign caught on in some parts of the country,  especially at Delhi University, the government’s tactics of mass  arrests, censorship and intimidation curtailed the opposition’s  popularity. After January, the Sikhs remained virtually alone in their  active resistance to the regime. Hailed by opposition leaders as “the  last bastion of
democracy”,they  continued to come out in large numbers each month on the day of the new  moon, symbolizing the dark night of Indian democracy, to court arrest.
When  attempts at pacifying the Akalis failed, Prime Minister Gandhi took the  opportunity of the dictatorship to deal the Sikhs of her country two  stunning blows. One was an award of Punjab waters which gave 75% of the  river flow to neighboring non-riparian states, at great cost to the  farmers of Punjab and in violation of international law on such rights.  The second blow was a ruling from the Defence Ministry that future  enrollment in the armed forces of Sikhs should be proportional to their  percentage of the population of India. Whereas Sikhs had traditionally  constituted 11% of the country’s armed forces from a population of only  2%, this was another assault on the Sikhs of India.
The  prime minister’s days of dictatorship came to an unexpected end when  she called elections for March 1977. With their voices returned to them,  the people of India trounced Indira Gandhi at the polls. According to  Amnesty International, 140,000 people had been detained without trial  during the twenty months of Mrs. Gandhi’s emergency. Of them, 40,000  were Sikhs. Indira Gandhi would never forget. When she returned to power  in 1980, she would come down hard on the Sikhs
According  to Amnesty International, 140,000 people had been arrested without  trial during the twenty months of Indira Gandhi’s Emergency. Of them,  40,000 had come from India’s two percent Sikh minority
6. Nirankari Kaand :
Till  now we saw partition and betrayal of promises made during independence,  struggle to get Punjabi suba , emergency atrocities and sustained  opposition to emergency by Sikhs . As a result of opposition to the  biased government policies a strong feeling of antipathy developed  between central government on one side and Sikhs and Punjab on the other  side .
So the central government  through its various agencies tried to modulate the social opinions .For  this purpose it set up and encouraged various anti Sikh sects (schools  of thoughts ) this included Nakli nirankaris (sometimes referred to as  just nirankaris but they are different from asli or the real nirankaris)  and Radha saomi . apart from financing these two pre existing sects in  their anti –Sikh activites .Central government agencies also encouraged  the penetration of new saints and holymen .This encouragement of sects  who openly preached against Sikh ism and /or tried to to wane away Sikhs  from Guru Granth sahib gave the Sikhs an impression that government is  against Sikhs .In the coming days this proved disastrous , as these  sects and their heads starting taking liberty with law .
It  should be noted that although Gurbachan Singh’s movement call  themselves Nirankaris, they do not have anything in common with the  original Nirankari movement that made enormous sacrifices and  significant contributions for Gur Panth’s reform.
With  increasing encouragement from government in 1978 nirankari sect head  gurbachan Singh decided to imitate Guru Gobind Singh ji .The Nirankari  leader is on record as saying that Guru Gobind Singh had made only Panj  Pyare (Five Beloved) and that he would make ‘Saat Sitaare’ (seven  stars). He had even dared to place his foot upon Guru Granth Sahib Ji.
On  13 th April 1978 Nirankaris took out a procession in Amritsar and held a  big congregation ,In this procession anti Sikh slogans were shouted and  in the congregation inflammatory remarks were made to protest this A  group of unarmed Sikhs went to the site of the congregation .But  Nirankari saint in collusion with police had armed people who attacked  these unarmed Sikhs leading to death of 13 Sikhs and many more injured .
The  astonishing thing is that the gathering of the Nirankaris continued for  three-and-a-half hours after this bloody massacre had occurred. It has  also become known that the D.C of Gurdaspur, Naranjan Singh I.A.S, and  other senior officers were present in the gathering during the massacre.  It is clear that the authorities of the Amritsar district allowed the  Nirankaris to hold their procession in the Sikhs main city of Amritsar  during Vaisakhi. The Police authorities are guilty of colluding with and  allowing the Nirankaris complete freedom to kill at will, and not  dealing with them properly at the right time. The Nirankaris were the  creation of the ‘democratic’ Government of India.The sect was created to  divide the Sikhs and produce infighting within the Panth.The Indian  Express (Chandigarh Edition) featured a report by Sat Pal Baghi in late  April 1978. He felt that the Indira Gandhi actively supported the  Nirankaris saying: “The genesis of the real trouble between the  Nirankaris and the Akalis goes back to the years when Indira Gandhi  headed the Union Government. She wanted to weaken the Shiromani Akali  Dal, but found that the Akalis could not be brought to heel. She thought  of an elaborate plan to strengthen the Nirankari sect not only in  Punjab , but throughout the country and abroad also. Official patronage  was extended to the Nirankaris much to the anger of the Akalis/Sikhs who  have always considered the Nirankaris as heretics.
7. Kanpur massacre :
Agitation  was started against the Nirankaris. Wherever they held their meetings,  Sikhs would go and strongly protest. Thus Gurbachan Singh was unable to  address the meetings held at Varanasi,Azamgarh and Allahbad. On 25th  September 1978, Gurbachan Singh reached Kanpur at 9.30pm flanked by  police officers ordered to provide protection. The news soon leaked out  and Sikhs started a protest march from Gurdwara Gobindpuri Sahib Ji,  which is three kilometres away from the Nirankari Bhawan in Kanpur.  Women and children were also amongst the protesters. The Nirankari chief  had again made full preparations for the Sikhs. When the Sikh  protesters reached the Nirankari Bhawan, the Nirankaris attacked them  with brickbats and shotguns.An armed volunteer of the Nirankaris attacked Jathedar Kishan Singh with a  spear, piercing his stomach.A fight ensued, and it was then that the  police officers started to shoot at the Sikh protesters. As a result,  thirteen Sikhs were martyred while a further seventy-four were injured.
Rise and role of Jarnail Singh Bhindrawala
Bhindraale can at best be described as a religious preacher who played an important role in
1) Awakening the Sikh youth about the ill effects of drugs and bringing them back to religious fold
2) Opposing the unjust policies of central government targeted towards Punjab .
He  learned principles of Sikh ism at Damdami Taksal of Bhinder Kalan  village and eventually went on to become its head. There he used to tour  villages to spread the teachings of ten Sikh gurus and to organise  Amrit Sanchar (the Sikh baptism ceremony ) He was very strict with  people who used to shun the Sikh discipline after taking baptism.
He  vehemently denounced drugs, alcoholic drinks and trimming of hair. He  took special notice of the Nirankari heresy which was undermining the  Sikh Structure. Opposition to the Nirankaris had started during the time  of his predecessor, Sant Kartar Singh Khalsa. Matters came to a head on  the Baisakhi day of 1978 when Nirankaris held a convention at Amritsar.  The Damdami Taksal under Sant Jarnal Singh Bhindrenwale and the Akhand  Kirtani Jatha, (another purely religious organization), protested  against government allowing the Nirankaris to hold their convention at a  time the Sikhs were celebrating the birth anniverssary of the Khalsa.  Some of them who marched to the site of the convention were fired upon  by Nirankari guardsmen killing 13 of them on the spot and wounding 78  others. The episode brought Sant Bhindrenwale into the political arena.
To  understand bhindrawale phenomenon one has to understand two extremely  important facts.The first is the position of the use of force for a  righteous cause in Sikh ideology and that nothing was unusual or  abnormal in the context of Sikh ism and its history . Second, a  continuous attempt by government to communalise the atmosphere so as to  lead to incidents of violence .
In one  of the interviews Bhindrawale said “You asked me about Khalistan. I  neither support it, nor am I against it .We want to stay with Hindustan ,  it is for central governent to decide whether they want us with them or  not .Yes if they give us khalistan we will take it . We wont make the  mistake of 1947.We are not asking for it but we’ll take it if they give  it to us .”
Apart from the Nirankari  incident mentioned in previous paragraph the other purely regional  incidents were given the guise of religious demand by central government  and denied this led to strong resentment not only in bhindrawale but  also in Sikh and Punjabi youth .There was let loose a reign of terror  and exploitation of Sikhs in Punjab and verbal war was fought by press  against Sikhs with Lala Jagat Narain the owner of hind samachar leading  the fight against Sikhs .He used to publish inflammatory articles  instigating Hindus against Sikhs .Lala Jagat Narain had appeared as  witness in case of Nirankaris and had ensured release of culprits .
Meanwhile.,  the Shiromai Akali Dal had been conducting a morcha since April 1982  against the digging of Satluj-Yamuna Link (S.Y.L.) canal which would  divert part of Punjab ‘s river waters to Haryana. The agitation inspite  of immense support from the Sikh peasantry was not bearing any tangible  fruit because the site (Kapori village on the Haryana-Punjab border  where the Indian Prime minister had inaugurated the digging of the canal  on 6 April 1982 was in a remote corner away from the Dal’s  headquarters. The Dal now decided to transfer the agitation, now  designated Dharam Yuddh or religious war, to Amritsar from 4 August  1982. Sant Jarnail Singh merged his own morcha with it, and thus became  in a way the joint dictator of the entire Panth though he still swore  loyalty to the former dictator of the Akali morcha, Sant Harchand Singh  Longowal.
A further provocation to the  Sikhs came from the behaviour of the Haryana government and police  during the Asian Games held at Delhi in November 1982. Sikhs travelling  from Punjab to Delhi or back were indiscriminately stopped, searched and  humiliated. Violence in the Punjab was on the increase. It was becoming  more and more clear that the government would seek a military Solution  of the situation in Punjab rather than a political one. Sant  Bhindranwale exhorted the people to be prepared for a showdown. On 15  December 1983, he with his men entered the Akal Takht and With the help  of a former major general of the Indian
Army,  Shahbeg Singh, prepared a network of defensive fortifications inside  the complex collecting in the meanwhile a large stock of arms,  ammunition and rations anticipating the possibility of a prolonged  siege. The government on its part made elaborate plans for all army  action while pretending all along its readiness for negotiations and  denying any intention of sending armed forces inside the Darbar Sahib  complex. The Punjab was placed Under the President’s rule on 6 October  1983. A ordinance declaring parts of the state a disturbed area was  promulgated, and the police was given power to search, arrest or even  shoot whom they will with immunity from legal action. Six additional  divisions of the army including especially trained para commandos were  inducted into Punjab by the end of May 1984. On 1 June, while the Sikhs  had started preparations in the Golden Temple for the observation of the  martyrdom anniversary of Guru Arjan, the fifth Sikh guru ,which fell on  the 3rd of June, strict curfew was clamped on Amritsar and surrounding  districts. The actual assault of the army’s operation nicknamed Blue  Star took place on the night of 5-6 June 1984. A pitched battle ensued  in which the army also used tanks and artillery. On the 7 Of June the  dead body of Sant Jarnail Singh Bhindranwale was located in the basement  of the Akal Takht.
Operation Blue star

Real Aim : A  human rights activist Ram Narayan Kumar notes, “Operation Blue Star was  not only envisioned and rehearsed in advance, meticulously and in total  secrecy, it also aimed at obtaining the maximum number of Sikh victims,  largely devout pilgrims unconnected with the political agitation.”
Stated aim : “checking and controlling extermist, terrorist and  communal vioulence in Punjab , providing security to the people and  restore normalcy.” Advertised targets: Jarnail Singh Bhindrawale living  in akal Takhat and his disciples numbering 100-150 Actual  target/victims: Sangat /visitors gathered to celebrate the martyrdom day  of fifth Sikh guru , Guru Arjan Dev ji numbering more than 10,000 in  number Forces employed: All three wings of the defence : army , navy and  airforce were employed in this operation.

Source: http://www.sikhsforjustice.org/?q=content/know-the-facts 

Sikhs For Justice | KNOW THE FACTS:

• October 31st, 1984 – November 4th, 1984: “November 1984 Sikh Genocide”.
• “November 1984 Sikh Genocide” was far from being a spontaneous expression of “madness” and popular “grief and anger” at Mrs. Gandhi’s assassination as made out to be by the authorities.
• It was an outcome of a well organized plan marked by important politicians of the Indian National Congress party and authorities in the administration.
• The brutal killing, looting and raping of Sikhs during the “November 1984 Sikh Genocide” took place in Delhi, Jharkhand, Madhya Pradesh, Haryana, Uttarakhand, Bihar, Uttar Pradesh, West Bengal, Himachal Pradesh, Rajasthan, Orissa, Jammu & Kashmir, Chattisgarh, Tripura, Tamil Nadu, Gujarat, Andhra Pradesh, Kerala and Maharashtra.
• As per official records over 3000 Sikhs were killed but the fact is, over 30,000 were killed (mostly burnt alive) throughout India and over 2,00,000 were displaced.
• Hundreds of  Sikh women gang raped throughout India by goons, police officers and civil administrators and told that next generation (after rape) will be loyal to Government.
• Hundreds of Gurudwaras and thousands of Guru Granth Sahibs were burnt and desecrated.
• Around 300 Sikh soldiers done to death in uniform by fellow soldiers.
• 120 Sikhs working at the Bokaro Steel Plant Jharkhand thrown alive into burning furnaces.
• Children as old as 13 days of age roasted alive on gas stoves in Kanpur and other cities in India.
• In Agartala, Tripura 40 Sikh families who took refuge in a police station to save their lives were burnt alive in the police station.
• In Jabalpur, Madhya Pradesh 12 Sikhs were hanged from the ceiling at the railway platform.
• Small children killed ruthlessly by pulling their legs apart whil their mothers being raped.
• In Haryana and Madhya Pradesh Sikh women taken into hostage and raped during November 1984, still held in captivity by the goons.
• Sikh women taken from refugee camps and raped even after November 6, 1984.
• Sikhs on public roads burnt alive, dragged out from trains and lynched on the railway platforms and set on fire
• Property of Sikhs worth millions was looted and destroyed.
• Massacre of Sikhs planned in a meeting organized at 24 Akbar Road, New Delhi on October 31, 1984 attended by members of Parliament and senior members of the Congress party including Jagdish Tytler, Sajjan Kumar, Kamal Nath, Dharam Das Shastri, Vasant Sathe, HKL Bhagat, Lalit Makhen, Arjun Das amongst others.
• State media showed inflammatory speeches and scenes. Popular movie stars like Amitabh Bachchan shown on state television raising slogans like  “Khoon ka badla khoon” (blood for blood) and “Khoon ke chintey sikhon ke ghar tak pahunchni chahiye” (Splashes of blood should reach the doorsteps of Sikhs).
• Police commondos from Police headquarters Madhuban, Haryana on the orders of Bhajan Lal, the then Chief Minister of Haryana send to commit the massacre of Sikhs.
• Expert arsonists and professional goons brought from outside and transported to different areas in Government buses. Supplied with inflammable materials to burn Sikhs, Sikh houses, businesses and Sikh temples.
• Police either actively participated in committing the massacre of Sikhs or stood as silent spectators while Sikhs burnt alive. Police even supplied diesel from police jeeps to the arsonists. Police disarmed the Sikhs before mobs attacked them.
• No curfew imposed or army called while most of the killings took place. When army called, deliberately designed to be ineffective.
• After 25 years the organizers and perpetrators of the Genocide roam free and even enjoy positions of power. None punished for killings of the Sikhs.
• Ten commissions have failed to bring Justice. Affidavits filed before commissions found lying at the residences of those accused of organizing and committing the massacre.