<p> 0n May 24, 1869, a one-armed Civil War veteran named John Wesley Powell and a ragtag band of nine mountain men embarked on the last great quest in the American West. No one had ever explored the fabled Grand Canyon; to adventurers of that era it was a region almost as mysterious as Atlantis -- and as perilous. </p> <p> The ten men set out down the mighty Colorado River in wooden rowboats. Six survived. Drawing on rarely examined diaries and journals, <i>Down the Great Unknown</i> is the first book to tell the full, true story. </p>