The answer is the French – Indian War. It eroded the
colonies of British America against those of New France.
Both borders were supported by military units from their parent countries
of Great Britain and France,
as well as by American Indian partners. At the beginning of the war, the French
North American colonies had a populace of approximately 60,000 settlers,
compared with 2 million in the British North American colonies. The outstripped
French mainly depended on the Indians. The European nations declared war on one
another in 1756 following months of restricted conflict, escalating the war
from a regional affair into an intercontinental conflict. This battles between
France and England in the new world resulting in the loss of all French
possessions.
The Open Door policy was drafted by the United States about activity in China. The policy supported equal privileges for all the countries trading with China and reaffirmed China's territorial and administrative integrity.