Final answer:
The Donner Party is infamous for resorting to cannibalism during their journey westward to California when trapped by harsh winter weather in the Sierra Nevada Mountains.
Step-by-step explanation:
The Donner Party is most known for resorting to cannibalism (eating humans) under dire circumstances. This incident occurred during their ill-fated journey in 1846-47, where a group of American pioneers migrated westward to California via a wagon train. Due to a series of mishaps and early winter snowfalls, they were trapped in the Sierra Nevada Mountains, leading to starvation and extreme measures of survival.