Question

what was the reason for siraj ud daullah defeat

Answer 1

Causes of the defeat of Siraj ud Daulah

He was not a much loved ruler
Ghaseti Begum (Meherun-Nisa), and another nephew, Shawkat Jang, wanted to remove Siraj from the throne
Mir Jafar, commander-in-chief of the army was courted assiduously by Ghaseti
Mir Jafar and Aminchand collaborated with the British against Siraj
Siraj's army did not raise arms aginst the British in the war field.