Why did Nawob Siraj lose the Battle of Plassey in 1757?

Battle of Plassey1757. Bullocks & elephants cannons. wikipedia.com
People of Indian history are aware that the battle of Plassey of 1757 between the Nawob of Bengal and the British forces commanded by Robert Clive was the very first decisive victory in the gradual growth of British imperialism in India and abroad.
Battle of  plassey, British artillery. oldindianarts.in
Under some pretexts, Clive, a clever military strategist  locked horns with ruler Siraj, fought a bloody war, dethroned him and at last had him killed by his own relatives who were greedy, grasping and jealous. Mir Jafer, a close relative of Siraj, now a puppet in the hands of the cunning British, at last, realized his folly and grave mistake of betraying his own blood. He, now,  turned against the British who had a plan to gobble up the vast Indian subcontinent with revenue from Bengal. As there were no hurdles in their path, it was a sort of open sesame for the British traders. For the proud Indians who remained disunited, it was the beginning of a downhill journey and it took nearly 200 years for them to drive the British out of India, - a Herculean and uphill task for our forefathers. 

In matter of wars, besides espionage, planning, military strategy, and proper execution, maintenance of arms and ammunition is equally important. If the machines do not work, their heads will be rolling on the ground. It is something akin to  cops going out on a beat with faulty six-shooters suddenly facing a group of street-wise muggers on a partly deserted downtown street.

On July 17, 1757 the British East India company with 3000 soldiers was pitted against the Nawab Siraj-ud-daulah's army with 5000 men backed by the French army. The Nawob's army fought well against the British army led by Robert Clive who kept changing his war plans to confuse the enemies. The war dragged on because of heavy rain and wet weather. On both sides artillery played a big role on the battlefield.

Anticipating rain and wet conditions, the British made their calculation right and came to the battle field well prepared to face any eventuality that might arise. When they knew that the weather condition was not good, they had standby weapons and protected their war weaponry, etc with tarpaulins and other protecting gear against the lashing rain and high humidity. On the other hand the Nawob ,unfortunately, did not have protection or cover for his weaponry, gun powder, etc. This slackened the rate of fire of his otherwise good weapons. Clive's men kept up continuous artillery fire and the Nawob's army was in disarray. In the aftermath of this war, the Nawob lost 500 men. That, Mir Madan Khan, military chief who fought with skill and tactic, was mortally wounded, was a big blow for Siraj. The British army's casualty was minimal.

Another factor that went against Siraj was his own allies who betrayed him at so crucial a time like this. Mir Jafer, his son and other dissident Amirs did not fight on the battle field and and indirectly sided with the British till his assassination. Like Brutus in the Shakespearean drama, here his blood relatives stabbed the helpless Nawob on his back.  

The third factor was the British had been planning to wage a war against the Nawob for a few months and had enough time to do their home work. For Siraj, time constraint was a major problem.

Here Robert Clive played a crucial role with unmatched cunning and Machiavellian skill and that is the reason why commander Robert Clive stood apart from other army British leaders in the sub continent. When Clive had put all this strategies into action, he was right on the target like US Army's Tomahawk cruise missile.