Trade led to battles because:
a. Bengal had emerged as an important trading centre, the East India Company had started its trading activities from the banks of river Hoogly, which had developed as an important sea port.
b. During the reign of Aurangzeb, the company was granted concessions that allowed them to trade freely without any duties and that enabled them to expand their trade in Bengal.
c. After the death of Aurangzeb, the Nawabs of Bengal tried to assert their dominance and refused to grant company's concessions, the Nawabs rather wanted to check the expanding tendencies of the East India company and accused it of deceit.
d. However, because of the Company's refusal to pay taxes and levying heavy duties on Indian goods entering Bengal, and continuous fortification of Calcutta, led to the outbreak of Battle of Plassey in 1757, which resulted in company's victory.
e. Like wise, Company's desire to expand trade, getting more trade privileges from local rulers,later resulted in Battle of Buxor.
f. This allowed company to firmly its position, to use the revenue of Bengal to purchase silk, cotton and to sell them abroad.