Dharam Yudh Morcha launched

Who: The Shiromani Akali Dal under Sant Harchand Singh Longowal, and Sant Jarnail Singh Bhindranwale, who merged his own morcha with it. The Encyclopaedia of Sikhism says this made him "in a way the joint dictator of the entire Panth".

What: The Akali agitation had begun against the digging of the Sutlej-Yamuna Link canal. On 4 August 1982 the Dal moved it to Amritsar and renamed it Dharam Yuddh, the religious war. ThePrint says Longowal launched the Dharam Yudh Morcha to implement the Anandpur Sahib Resolution. Volunteers courted arrest in jathas.

Bhindranwale's own morcha came first. After police arrested Bhai Amrik Singh, president of the All India Sikh Students Federation, on 19 July 1982, Bhindranwale moved to Guru Nanak Nivas in the Darbar Sahib complex on 20 July and announced his morcha at a Panthic convention on 25 July.

In November 1982, during the Asian Games in Delhi, Sikhs travelling between Punjab and Delhi were, in the Encyclopaedia's words, "indiscriminately stopped, searched and humiliated". Punjab was placed under President's rule on 6 October 1983. On 15 December 1983 Bhindranwale and his men entered the Akal Takht, and with the help of a former army major-general he prepared defensive fortifications inside the complex. The morcha ended with the army assault, Operation Blue Star, on the night of 5 to 6 June 1984.

Where: Amritsar and the Darbar Sahib complex, with jathas courting arrest across Punjab.

Why it mattered: The Tribune wrote that the Dharam Yudh Morcha of 1982 would "stand out as the last morcha of the Akalis". It was the Akali Dal's largest mass agitation, and the government answered it with talks that never settled and then with the army.

The number of arrests is reported very differently. Wikipedia's account, which cites academic histories, gives over 25,000 volunteers arrested by early October 1982, and totals for the whole morcha of over 150,000 (Jugdep Chima, 2008), over 200,000 (Dhillon, 2006) and over 250,000 (Singh, 2008). Those books are not freely readable online, so treat the range as an estimate, not a count.