Complex sentence: The Snake War was not defined by one large battle but was a series of guerrilla skirmishes by the Indians, and patrols by detachements of American soldiers which took place across California, Utah, Nevada, Oregon, and Idaho.
Split into simpler sentences: The Snake War was not defined by one large battle. Rather, it was a series of guerrilla skirmishes by the Indians, which took place across California, Utah, Nevada, Oregon, and Idaho.