JASSĀ SIṄGH RĀMGAṚHĪĀ (1723-1803), founder of the Rāmgaṛhīā chiefship and one of the prominent military leaders of the Sikhs in the second half of the eighteenth century, was born in 1723 at Īchogill, a village 20 km east of Lahore. His grandfather, Hardās Siṅgh (d. 1716) had received pāhul, the vows of the Khālsā, at the hands of Gurū Gobind Siṅgh and had fought in the campaigns of Bandā Siṅgh Bahādur. His father, Bhagvān Siṅgh was killed in a fight against Nādir Shāh during his invasion of India in 1739. Young Jassā Siṅgh then joined the jathā of Nand Siṅgh Sāṅghanīa and learnt the art of warfare at an early age. In 1745, he was deputed to settle terms with Adīnā Beg, the faujdār of the Jalandhar Doāb, who was harassing the Sikhs under instructions from Nawāb Zakarīyā Khān, the Mughal governor of Lahore. The wily faujdār, Adīnā Beg, prevailed upon Jassā Siṅgh to accept office under him, with a minor command of a regiment consisting of 100 Sikhs and 60 Hindus. The Sikhs were greatly annoyed at the conduct of their envoy, but Jassā Siṅgh did not remain with Adīnā Beg for long. When in October 1748, the Sikhs gathered at Amritsar to celebrate the festival of Dīvālī, Mīr Mānnū, the new provincial governor, marched upon the city to expel the Sikhs. The Sikhs disappeared into the neighbouring jungle, but 500 of them took shelter within their newly built fortress, Rām Rauṇī, and defied the Mughal force. The mud-fortress was besieged and skirmishes continued for four months in which two hundred Sikhs lost their lives. The survivors requested Jassā Siṅgh to come to their rescue. Jassā Siṅgh left Adīnā Beg, and made an appeal to Kauṛā Mall, the Dīwān of Lahore and a Sahajdhārī Sikh, to save the Sikhs from destruction. At the Dīwān's intercession, Mīr Mānnū raised the siege, though the fortress of Rām Rauṇī was completely destroyed.

         Mīr Mānnū's death in November 1753 plunged the Punjab into anarchy. The Sikhs again emerged into the open and decided to rebuild the Rām Rauṇī fort. Jassā Siṅgh was assigned to this task and he, with the help of his contingent, reconstructed the fortress and named it Rāmgaṛh. Since then Jassā Siṅgh, earlier known as Īchogillīā after the name of his village, or ṭhokā (carpenter, the caste he came from) began to be called Rāmgaṛhīā in appreciation of the work done by him.

         In April 1758, Ādīnā Beg became governor of the Punjab. He sent a strong force under Mīr 'Azīz Bakhshī to clear the forests in which Sikhs had taken shelter. A large number of them including Jassā Siṅgh Rāmgaṛhīā, Jai Siṅgh Kanhaiyā and Amar Siṅgh Kiṅgrā, fled to Amritsar and took shelter in the fortress. Rāmgaṛh was besieged. Jassā Siṅgh and Jai Siṅgh made numerous sallies killing a large number of the besiegers, but were ultimately forced to evacuate. After Ādīnā Beg's death in September 1758, the roving bands of the Sikhs returned. Jassā Siṅgh Rāmgaṛhīā and Jai Siṅgh Kanhaiyā united and within a short time they seized large slices of territory in four out of the five Doābs; they occupied the fertile tract called Riāṛkī to the north of Amritsar embracing the district of Gurdāspur. Within a decade Jassā Siṅgh became one of the leading figures of the Dal Khālsā. In 1770, he led plundering expeditions into the hills. The local rājās sought safety in submission and Jassā Siṅgh collected a tribute of 2,00,000 rupees from the Kāṅgṛā states. He built a fort at Talvāṛā on the left bank of the Beās and stationed his brother, Mālī Siṅgh, with 4,000 horse, in the fort. Jassā Siṅgh Rāmgaṛhīā along with other Sikh sardārs, fought many a pitched battle against the Afghān invader, Ahmad Shāh Durrānī.

         As the Afghān threat receded, the Sikh sardārs began fighting among themselves. The Rāmgaṛhīā Kanhaiyā cleavage over their adjoining territories in the districts of Gurdāspur and Hoshiārpur widened. In the battle of Dīnānagar in 1775, Jassā Siṅgh Rāmgaṛhīā joined the Bhaṅgī sardārs against the forces of the Kanhaiyās and the Sukkarchakkīās. Soon a rift appeared between Jassā Siṅgh Rāmgaṛhīā and Jassā Siṅgh Āhlūvālīā when the latter wrested Zahūrā, a Rāmgaṛhīā territory, and conferred it upon Baghel Siṅgh Karoṛsiṅghīā. Jassā Siṅgh Rāmgaṛhīā and Jassā Siṅgh Āhlūvālīā became sworn enemies of each other. Jai Siṅgh Kanhaiyā joined Jassā Siṅgh Āhlūvālīā and the Rāmgaṛhīā Sardār had to flee the Punjab.

         Driven out of the Punjab, Jassā Siṅgh became a soldier of fortune. He took possession of Hissār and raised a large body of irregular horse, his depredations extending to the gates of Delhi and its suburbs and into the Gangetic Doāb. Jassā Siṅgh and other Sikh chiefs conquered Delhi and entered the Red Fort. Jassā Siṅgh Āhlūvālīā ascended the throne on 11 March 1783, but Jassā Siṅgh Rāmgaṛhīā challenged his right to do so at which the Āhlūvālīā chief vacated the royal seat. Jassā Siṅgh Rāmgaṛhīā then invaded Meerut and levied an annual tribute of 10,000 rupees on the Nawāb. Soon a body of 30,000 horse and foot under him and Karam Siṅgh crossed into Sahāranpur district, ravaging it freely.

         After the death of Jassā Siṅgh Āhlūvālīā in October 1783, there were further fissures in the Dal Khālsā. Jai Siṅgh Kanhaiyā and Mahāṅ Siṅgh Sukkarchakkīā fell out. Mahāṅ Siṅgh won over to his side Rājā Saṅsār Chand of Kāṅgṛā and invited Jassā Siṅgh Rāmgaṛhīā to come back to the Punjab and make a bid to recover his lost possessions. Jassā Siṅgh Rāmgaṛhīā returned to the Punjab and allied himself with the Sukkarchakkīās in order to destroy his old foe, Jai Siṅgh Kanhaiyā. Together they marched upon the Kanhaiyā citadel of Baṭālā in 1787. Jai Siṅgh was defeated and his son Gurbakhsh Siṅgh killed. Jassā Siṅgh recovered all his lost territories and set himself up at Baṭālā, which he fortified by a thick wall.

         At the height of his power, Jassā Siṅgh's territory in the Bārī Doāb included Baṭālā, Kalānaur, Dīnānagar, Srī Hargobindpur, Shāhpur Kaṇḍī, Gurdāspur, Qādīāṅ, Ghumāṇ, Mattevāl, and in the Jalandhar Doāb, Uṛmuṛ Ṭaṇḍā, Sarīh, Mīanī, Gaṛhdīvālā and Zahūrā. In the hills Kāṅgṛā, Nūrpur, Maṇḍī and Chambā paid him a tribute of two lakh of rupees.

        Jassā Siṅgh died on 20 April 1803 at the age of 80.