The revenues of the Indian princes were largely derived from tolls on the transit of merchandise. The company, which had the right of free exportation and importation, passed its goods free inland under the certificate of the head of a factory. The system was abused. The company paid its servants insufficient salaries, and they made up for it by engaging in private inland trade, using the company's passes to cover their goods. Armed with its power, they forced the natives to deal with their native agents, to buy dear and sell cheap; they monopolised the trade in the necessaries of life, and grew rich upon the miseries of the helpless people. Private trade and extorted presents enabled many a man who as a mere youth had obtained a writer's place to return to England after a few years with a handsome income. Mir Kasim saw his people starving, his officers ill-treated, and his treasury robbed, and prepared for revolt. Conscious of the impending danger, Vansittart made an agreement with him as to tolls. The council at Calcutta indignantly repudiated the agreement, and Mir Kasim was furious. Open hostilities began in June, 1763. One of the council, who was sent on an embassy to Kasim, was killed by his troops. Patna was seized by the English; it was retaken, and some 200 English were made prisoners. A little army under Major Adams, routed the nawab's forces, and on October 11 Monghyr was taken. Mir Kasim caused all his prisoners, save five, to be massacred, and fled for refuge to Shuja-ud-Daula the nawab wazir of Oudh. Patna was taken by storm and Bengal was completely subdued.