While Europeans weapons gave them an advantage over the weapons of the First Nations Peoples, what invisible warrior ultimately led to the destruction of the vast majority of the Native American population?

Infectious diseases

Explanation:

Infectious diseases have decimated many Indian tribes. Infectious diseases are the biggest culprit of the high mortality of native tribes in America. The natives did not have a developed defense mechanism of the organism against infectious diseases. Europeans gained resilience hundreds of years earlier. Smallpox and the flu are just some of the diseases that have decimated the American community's sometimes complete natives.

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united states reinforcements contributed greatly to three allied victories in france at: cantigny (first major american battle), argonne (the largest in the united states military history, involving 1.2 million american soldiers), and château-thierry (one of the first actions under general pershing).