The impact of the Battle of Tippecanoe, which took place in 1811 between American forces led by Governor William Henry Harrison and Native American warriors associated with Shawnee leader Tecumseh, is best captured by the answer:
C It resulted in increased attacks on American settlements in the Indiana Territory.
While the battle was a setback for Native American unity and resistance, it also ignited further conflict between Native Americans and settlers, leading to increased tensions and attacks in the region. Additionally, it is worth noting that it did spur some Native American groups to resist American encroachment more fiercely, which aligns with some aspects of the other choices as well. However, in direct relation to the question, C is the most accurate impact.