Unification of Nepal
The unification of Nepal was the process of building the modern Nepalese state, by invading fractured Malla kingdoms including the Baise Rajya's 22 kingdoms and the Chaubisi Rajya's 24 kingdoms. It began in 1743 CE, by Prithvi Narayan Shah, King of Gorkha. On 25 September 1768, he officially announced the creation of the Kingdom of Nepal and moved his capital from Gorkha to a city in Kathmandu Valley.
The Shah dynasty that Prithvi Narayan Shah founded would go on to absorb the various warring Malla kingdoms that once occupied parts of present-day Nepal into a nation-state that stretched up to the Sutlej River in the west and Sikkim-Jalpaiguri in the east. Before the Gorkha Empire, the Kathmandu Valley was known as Nepal after the Nepal Mandala, the region's name in Newar language.
Background
The regions that constitute present-day Nepal were scattered as numerous independent kingdoms prior to unification. The Kathmandu Valley, then called Nepal Mandala, alone contained three independent kingdoms: Kantipur, Lalitpur, and Bhadgaon. Makwanpur, to the south of the valley, was ruled by the Sen dynasty. To the east of the valley were two relatively larger kingdoms: Vijayapur, and Chaudandi. Both of these kingdoms once belonged to Makawanpur, but Mukunda Sena had partitioned his kingdom among his sons and relatives and had divided the once large Makawanpur into various principalities.Between the rivers Trishuli and Bheri, known as the Gandaki region, were the Chaubisi principalities. Further west, in the Karnali region, were the Baise principalities. Baise and Chaubise literally translate to twenty-two and twenty-four kingdoms respectively, but the exact number of kingdoms wasn't the same as the regions' collective names. The Baises were once a part of the Khasa Kingdom, ruled by the Khas Mallas from the Sinja valley, before its fragmentation. The Chaubisi principalities belonged to various political entities. Some belonged to the Senas, some to the Khas Mallas, and some to the Shahis.
These principalities experienced constant change and instability. Several kingdoms made leagues in order to protect themselves from foreign invasions and for mutual growth. However, due to the economic and geographic conditions prevalent at that time, disputes and battles between the kingdoms were frequent. The Malla kings of the valley engaged in incessant conflicts and skirmishes among themselves and had, at several instances, requested the intervention of Gorkha to settle their disputes.
Battle campaigns
Nuwakot
Prithvi Narayan Shah's annexation campaign began with the nearby kingdom of Nuwakot. Nuwakot marked the eastern boundary of the Gorkha Kingdom and was part of the trade route between Tibet and Kathmandu. It was also the western gateway to the Kathmandu Valley. Nara Bhupal Shah, Prithvi Narayan Shah's father, had attempted to invade Nuwakot in 1700, but failed. At that time, Nuwakot was under the administrative control of Kantipur. Kantipur supported Nuwakot against the invasion. Following his defeat, Nara Bhupal Shah gave up his efforts and handed administrative power over to his eldest son, Prithvi Narayan Shah and Chandraprabhawati, his eldest queen.In the very year of his coronation, Prithvi Narayan Shah sent Gorkhali troops under Kaji Biraj Thapa Magar to attack Nuwakot. The campaign failed.
File:Bamshidhar Kalu Pande.jpg|thumb|upright|Kalu Pande wearing Khukuri, a Pande Chhetri aristocrat; Kaji of Gorkha Kingdom.Kalu Pande was then made Commander-in-Chief of the Gorkhali Army. Jayant Rana Magar was made General of the kingdom of Kantipur by Jaya Prakash Malla to defend Nuwakot against Gorkha. Kalu Pande advised Prithvi Narayan Shah to raise a standing army by conscripting men from other regions. A newly fortified Gorkhali force again attacked Nuwakot in 1744 from three sides and managed to capture the hill fort on September 26, 1744. However, the next year, King Jaya Prakash Malla of Kantipur sent a force under Kashiram Thapa to retake the fort, after defeating the Gorkhali forces at Naldum. Kashiram was repelled and the Gorkhali seized permanent control of Nuwakot.
Tanahun
While Prithvi Narayan Shah was occupied with Nuwakot, Tanahun, a small kingdom to the west, took advantage of the king's absence to invade the Gorkha kingdom. Tanahun troops crossed the Chepe river and captured Sirhanchowk. But reinforcements from both Nuwakot and Gorkha managed to rout the invaders and considerably weaken Lamjung.Prithvi Narayan Shah wanted to use the occasion to invade Tanahun and annex it. However, he was advised against an open attack as King Tribikram Sen of Tanahun was an old friend of his father's. Prithvi Narayan Shah thus invited Tribikram Sen to the banks of the Trishuli river on the pretext of a friendly visit and then took him into custody. Tribikram Sen was imprisoned in Nuwakot and Tanahun was officially annexed to the burgeoning Gorkha Empire.
Makwanpur and Hariharpur
As part of his goal of taking the Kathmandu Valley, Prithvi Narayan had planned to first conquer all of the kingdoms and principalities surrounding the Kathmandu Valley.Sensing danger, King Digbardhan Sen and his minister Kanak Singh Baniya of Makwanpur sent their families to safer grounds before they were encircled by the Gorkhalis, who launched an attack on 17 August 1762. The battle lasted for around eight hours and while Makwanpur was annexed, King Digbardhan and Kanak Singh escaped to Hariharpur Gadhi.
After occupying the Makwanpur, the Gorkhali forces planned to take Hariharpur Gadhi, a strategic fort on a mountain ridge of the Mahabharat range, also south of Kathmandu. It controlled another route to the Kathmandu valley. On 4 October 1762, the Gorkhalis launched Hariharpur. The soldiers there fought valiantly against the Gorkha forces, but were ultimately forced to vacate the fort. About 500 soldiers from Hariharpur died in the battle.
Digbardhan Sen sought the help of Mir Qasim, the Nawab of Bengal, to help defend against the Gorkhalis. Mir Qasim, sought to gain loot and plunder from the invasion, as he was using lavish gifts to get on the East India Company's good side. In December 1762, he sent around 3,500 troops under Gurgin Khan, an Armenian man who had helped train Mir Qasim's army, to launch an attack on Makwanpur, which had only recently been captured by the Gorkhalis.
Mir Qasim's forces arrived in Makwanpur in January 1763 and launched an attack on Dadhuwa Gadhi, one of three defensive positions the Gorkhalis had set up around Makwanpur fort. Gurgin Khan's 3,500 soldiers managed to capture Dadhuwa Gadhi from 400 or so Gorkha soldiers. On 21 January 1763, 3,300 of Gurgin Khan's soldiers launched an attack on Makwanpur palace. The Gorkhalis, under Prithvi Narayan's brother Nandu Shah, held off the invaders. Supplemented by reinforcements, the Gorkhalis counter-attacked Gurgin Khan in the dead of the night while his soldiers were asleep. The Gorkhalis managed to rout Gurgin Khan's forces, who retreated back to Bengal.
Kathmandu Valley (Nepal Mandala)
The Shah kings had long set their sights on the Nepal Valley, now also known as Kathmandu Valley, which was host to three wealthy but constantly warring city-states ruled by the Malla dynasty. After conquering Nuwakot, which was the western gateway to the Kathmandu Valley, the Gokhalis aimed for Kirtipur as their next target. Kirtipur was a small fortified city on the outskirts of the three major city-states ruled by Newar Malla kings.Despite his initial assessment that the valley kings were well prepared and the Gorkhalis were not, Kalu Pande agreed to lead the battle. In 1757, The Gorkhalis set up a base on Naikap to mount their assault on Kirtipur. They were armed with swords, bows and muskets. The two forces fought on the plain of Tyangla Phant in the northwest of Kirtipur. Kalu Pande was killed in the battle while Prithvi Narayan himself narrowly escaped with his life into the surrounding hills disguised as a saint.
In 1764, Prithvi Narayan assaulted Kirtipur a second time. The attacking forces were under the command of Surapratap Shah, Prithvi Narayan's brother. The Gorkhalis were defeated once again and Surapratap lost his right eye to an arrow while scaling the city. A noble of Lalitpur named Danuvanta crossed over to Shah's side and let the Gorkhalis into the town.File:Ram Krishna Kunwar.jpg|thumb|Sardar Ram Krishna Kunwar, senior military commander of Gorkhali forces
The victory in the Battle of Kirtipur made Shah's two-decade-long effort to take possession of the Kathmandu Valley possible.
After the fall of Kirtipur, Shah took the city-state of Kathmandu in 1768. That same year he also took possession of Lalitpur. In 1769 he took possession of Bhaktapur, completing his conquest of the Nepal Valley. In a letter to Ram Krishna Kunwar, King Prithvi Narayan Shah was unhappy at the death of Kaji Kalu Pande in Kirtipur and thought it was impossible to conquer Kathmandu Valley after the death of Kalu Pande. After the annexation of Kathmandu Valley, King Prithvi Narayan Shah praised in his letter about the valour and wisdom shown by Ramkrishna in the annexation of Kathmandu, Lalitpur and Bhaktapur in 1768-69 A.D. Similarly, Vamsharaj Pande, Kalu Pande's eldest son, was the army commander who led attack of Gorkhali side on the Battle of Bhaktapur on 14 April 1769 A.D.
After his conquest of the Kathmandu Valley, Prithvi Narayan Shah conquered other smaller territories south of the valley to keep other smaller fiefdoms near his Gurkha state out of British rule. After his kingdom spread from north to south, he made Kantipur the capital of the expanded country, which was then known as the Kingdom of Gorkha.