Final answer:
The creation of the Miami Triad was a result of the increasing tensions between American settlers and Native American tribes in the Ohio Valley during the Northwest Indian War.
Step-by-step explanation:
The event that occurred in the winter of 1847 that led to the creation of the Miami Triad was the Northwest Indian War. The Miami Triad was formed as a result of the increasing tensions between American settlers and Native American tribes in the Ohio Valley, including the Miami, Shawnee, and Wyandot tribes. This confederacy declared that they would deal with the United States as a united group and not as individual tribes, and they opposed treaties signed by only one individual or group.