 At first the NWC had collaborated with Astor, to avoid the East India Company's monopoly, and they shared some of the same trade routes to China.Over time, American pressure at their shared Pacific trading post on the mouth of the Columbia River was applied to the NWC in a subtle but systematic fashion, and to retain his freedom, McGillivray contemplated negotiating with the East India Company.The rivalry between the NWC of Montreal and the English-controlled HBC gradually degenerated into a bitter and violent struggle, first under McTavish and then McGillivray.