The Seven Oaks Massacre was the bloodiest incident in the forty-year struggle between the Hudson's Bay and North West Companies. It initiated a period of extremely tense relations and provoked the Hudson's Bay Company to attack Fort William in August 1816.The violent cycle continued until 1821, when the companies merged under the name of the Hudson's Bay Company.he attack was a part of the companies' intense struggle for the control of the Northern Plains fur and meat trade; its immediate goal was to expel the Nor'westers from the Red River Settlement by cutting off their supply lines from the Plains.