Basantapur Palace, where the incident took place

During the 19th century, Basantapur Palace and Hanuman Dhoka premises had long served as the administrative center of Kantipur, (later unified as Nepal in 1768 A.D) since 15th century. This place now serves as a UNESCO world heritage site and is known under Kathmandu Durbar Square. Durbar Square area is notable for continuously serving as the administrative center of the country until 1972 A.D. Notable ruling classes of the country housed their palace in the Durbar Square Area including Malla Dynasty, Rana and Shah Dynasty. 

Leading to the incident

King Rajendra Bikram Shah (4th successor of King Prithivi Narayan Shah, the unifying King) had two wives, Samrajya Laxmi Devi and Rajya Laxmi Devi (in respective order of marriage). It is stated that his queens, notably  the eldest queen Samrajya Laxmi Devi had more power in the palace than the King himself, which introduced instability in the palace. After queen Samrajya Laxmi Devi died in 6th October 1841 A.D, queen Rajya Laxmi Devi was stated to abuse her power by favoring her son Prince Ranendra for the throne. This decision of queen Rajya Laxmi Devi contradicted Prince Surendra Bikram Shah (born to deceased Queen Samrajya Laxmi Devi) from legally being in line to the throne according to official ruling order. This caused even more instability to the palace and further divided the army officials. 

Mathbarsingh Thapa was appointed as Mukhtiyar General (Prime Minister/ Commander in Chief of Army) on 25th December 1843 A.D. Mathbarsingh Thapa was then finally approached by the queen with proposal to make Prince Ranendra in line to the throne. Mathbarsingh Thapa didn't accept this proposal and instead suggested King Rajendra to step down from his throne. This decision ultimately cost him his life in the hands of his nephew, Janga Bahadur Rana with support from King Rajendra and Queen Rajya Laxmi Devi.

Build up for the infamous Kot Parva, one of many massacres in the ancient Kingdom of Nepal

The death of Prime Minister, Mathbarsingh Thapa caused even more unrest and instability in the palace. It is stated that Queen Rajya Laxmi Devi had support from a powerful Commander Gagan Singh Bhandari. Commander Gagan Singh Bhandari had a lot of influence within state affairs with support of the queen which was against King Rajendra's decisions. Finally, after 4 months unrest, Chautaria Fatteh Jung Shah was appointed as Mukhtiyar (Prime Minister and Commander in Chief) of the country. Through possible internal intervention, Queen favored commander Gagan Singh Bhandari and Commander Janga Bahadur Rana were allocated more troops than Commander in Chief. Notably, Queen favored General Gagan Singh Bhandari exercised the greatest power among Janga Bahadur and Fateh Jung Shah. 

Mysterious death and following bloodshed

Commander Gagan Singh Bhandari and his privilege for being favored by the queen didn't go well with the army. This power imbalance ultimately lead to his death on the night of 14th September 1846 A.D in his private temple while offering prayers. His death remains greatest mysteries among other mysterious deaths of high ranking leaders throughout the history of Nepal. The same night, the queen gathered a meeting to avenge the death. The meeting was held on Kot arsenal of Basantapur Palace of Kathmandu. Somehow, the meeting turned into a mass murder and one of the greatest political turning point in the history of Nepal. Commander Janga Bahadur Rana and his army were able to assassinate various high ranking officials of the country including Prime Minister of the country, Mukhtiyar Fatteh Jung Shah and other senior ministers and army generals in that Kot assembly.

Aftermath

This bloodshed which is speculated to be plotted by Janga Bahadur Rana made him the most powerful Prime Minister of the country and eventually turned the whole country into a single family rule for 104 years. The country fell in the hands of Rana rulers for 104 years which was total Autocracy with limited or no rights to the citizens of country. Notably restricting access to education and basic human rights to citizens. Rana rulers used Basantapur Durbar Square as administrative center similar to Malla dynasty. Many monuments have been accumulated throughout the 1800s due to this regime. 

Present times

Basantapur Durbar Square, where this incident took place later on served as administrative center for Shah monarchs after Democracy against Rana Regime in 1951 A.D. The autocratic Rana Regime caused several people to lose their lives for their demand of freedom who were later honored at Martyrs Gate, Sundhara Kathmandu. Nepal has been a democratic country for the most part since 1951 A.D. The country has transitioned into Federal Republic since 2006 A.D. Later in 1972 A.D, King Mahendra Bir Bikram Shah shifted Kings office from Nautalle Darbar, Basantapur to Narayanhiti Palace, Durbar Marg. At current times, Basantapur Durbar Square has opened to general public and serves as a major tourist attraction. Basantapur Durbar is listed as UNESCO World Heritage Site as it hosts monuments as old as 7th Century.