Kazi Kalu Pande, the Gorkhali commander, chalked out a strategy to mount a sudden attack against the defenders from an unexpected direction without giving the enemy opportunity for counterattack. When Kazi Kalu Pande began to climb up from the North, it was dawn of the 26th of September 1744. The defenders of Nuwakot were still sleeping. The Gorkhali forces reached Mahamandal, a tactical outpost in Nuwakot, and mounted a surprise attack there. Shankha Mani, the commander of the defenders, began to encourage his panic-stricken soldiers to stand up and fight against the Gorkhalis, but to no avail. He himself took a sword, charged forward and wounded a few Gorkhali soldiers. He had already sustained injuries. He advanced towards Dal Mardan Shah, brother of Prithvi Narayan Shah, and challenged him. Dal Mardan Shah was just 13 years old. Dal Mardan Shah answered the challenge and with a swift strike on Shankha Mani’s head, killed him on the spot. Kalu Pande’s plans had proved successful.
Another group of Gorkhali soldiers led by Chautaria Mahadam Kirti Shah, another brother of Prithvi Narayan Shah, crossed Dharampani but met with strong resistance. The battle continued for a while and ultimately the Gorkhali forces prevailed. Many defenders died and the remaining fled.
The third group, led by King Prithvi Narayan Shah himself, began to advance swiftly towards Nuwakot Gadhi (fort) after receiving news of the capture of Mahamandal. The death of Shankha Mani had taken the wind out of the defenders’ sail. They began to flee towards Belkot instead of fighting. Kazi Kalu Pande reached Nuwakot with a small contingent of forces. Mahodam Kirti Shah also arrived. King Prithvi Narayan Shah entered the Nuwakot Gadhi fortress. Nuwakot was annexed to the Gorkha State. The first foothold in the process of unification of Nepal had been secured.
Over the next few years, this success was followed by a deliberate and practical strategy to lay general siege on the Kathmandu Valley from all directions. Another important step in the initial unification campaign was the conquering of Kirtipur, the fortress in the southern part of Kathmandu valley. Gorkhali troops had failed twice to secure Kirtipur. King Prithvi Narayan Shah changed his plan and encircled and blockaded the whole fort. A six-month long siege by the Gorkhali forces created panic among its inhabitants. The Kirtipur Commander, on 12th March, 1766, opened the gates of the fort at mid-night and surrendered to the Gorkhali forces. Kirtipur was annexed to Gorkha without any battle.
Similar blockade tactics also helped secure Makawanpur, south of Kathmandu Valley. Well known names like Mohaddam Kirti Shah, Surpratap Shah, Dalamardan Shah, Rana Rudra Shah, Nandu Shah, Kaji Bamsa Raj Pandey, Kaji Kehar Singh Basnyat, Kaji Nahar Singh Basnyat and Kaji Abhiman singh Basnyat were dispatched with about 1,100 fighting troops to encircle the Makawanpur fortress by the dawn of 20th August 1762.
King Digbardhan Sen and his minister Kanak Singh Baniya had already sent their families to safer grounds before the encirclement of their fortress. The Gorkhalis launched an attack on 21st August 1762. The battle lasted for eight hours. King Digbardhan and his minister Kanak Singh escaped to Hariharpur Gadhi. Makawanpur was thus annexed to Nepal.
After occupying the Makawanpur Gadhi fort, the Gorkhali forces started planning for an attack on Hariharpur Gadhi, a strategic fort on a mountain ridge of the Mahabharat range, also south of Kathmandu. It controlled the route to the Kathmandu valley. At the dusk of 4th October, 1762, the Gorkhalis launched the attack. The soldiers at Hariharpur Gadhi fought valiantly against the Gorkha forces, but were ultimately forced to vacate the Gadhi after mid-night. About 500 soldiers of Hariharpur died in the battle.