What contributed to the decline in population of the native americans

War and violence.

Explanation:

While epidemic disease was by far the leading cause of the population decline of the American indigenous peoples after 1492, there were other contributing factors, all of them related to European contact and colonization. One of these factors was warfare.

the  wilmot proviso  was designed to eliminate  slavery  within the  landacquired as a result of the mexican war (1846-48). fearing the addition of a pro-slave territory, pennsylvania congressman david  wilmot proposedhis amendment to the bill.

i believe that the correct answer is a canadian hero.

explanation: he is celebrated as a national hero in canada for successfully thwarting a united states takeover of canada during the war of 1812.