Answer:
PNS personally commanded many battles. The battles taught him how to handle complex situations and how he could come out victorious.
PNS focused on his goal and used all means (Saam, Daam, Danda, Bhed) for his campaign. As he fought battles, he understood why integrating the nearby kingdoms could be beneficial against the rising British hegemony in the region. He also realized that the diversity of Nepal could be exploited by British to divide the kingdom.
Explanation:
Prithvi Narayan Shah was not a strategist in the beginning. As soon as he became the king of Gorkha, he wanted to capture Nuwakot. In 1800 B.S., the first troop he sent under Biraj Thapa could not cross the Trishuli River. PNS, however, was not satisfied with the delay and sent another troop under Maheshwar Panta. The Gorkhali troop lost to the nature (Trishuli) as well the soldiers of Nuwakot.
After the loss, PNS became a military strategist. He went Benaras, brought some weapons and trained his soldiers so that they obey all commands without fear. He also developed the Marwat system for helping the soldier’s family if he died in a battle. He also used Yogis, the devotees of Gorakhnath, as spies.
He did not know how to use geography to strategical advantage before he himself led the Second Battle of Nuwakot in 1801 B.S. Had Kalu Pandey not found a way to divert huge number of Nuwakote soldiers, PNS could have died in the battle.
He had already understood politics, though. Before the Second Battle of Nuwakot, PNS had realized that the Chaubise Rajyas could be threat to his campaign and he might have to kill his kins in Kaski, Lamjung and Tanahun. To avoid the “sins”, he changed his gotra from Bhardwaj to Kasyap.
He also understood that Nepal (the then Kathmandu Valley—Kantipur, Patan, and Bhaktapur) would be against him as soon as he captured Nuwakot. So he kept a cordial relation with Ranjit Malla of Bhaktapur, who was also his Meet Baa (best friend’s father/father’s best friend)
PNS used the anarchy established by the Pradhans to make his brother Dal Mardan Shah the king of Patan from 1820–1822. When PNS attacked Kirtipur in 1822, Dal Mardan Shah did not oppose even though the Pradhans had urged him to do so. On Poush 3, 1822, PNS won the third battle of Kirtipur. Less than four years later, PNS was the king of Nepal.
PNS also understood how the people of Nepal Mandal lived. When he won the surrounding areas, he imposed a complete economic blockade which was one of the biggest reasons behind his victory over Kantipur, Patan and Bhaktapur.
Through treaties and diplomatic understandings, he was able to solve a lot of problems with the Chaubises and Baises, the British, the Tibetan and the Newas.