The lackluster Allied showing on Sicily and the escape of most of the island's garrison encouraged Hitler to alter his plans and defend Italy vigorously. With its rugged mountain ridges, deep valleys, and numerous rivers, Italy contained tens of thousands of natural defensive positions. The Wehrmacht exploited these to the full during the ensuing campaign, bogging down the Anglo-American armies in an endless series of costly, time-consuming engagements. Even the rank and file German soldie...

One of the men most responsible for the closing of the frontier was John Wesley Powell, arguably the best-known American explorer after Lewis and Clark. He was lionized for a long portion of his life and vilified for another. Powell was a competent man, self-confident and able to instill confidence in his abilities to lead, and his expeditions helped Americans better understand the West, an impressive achievement for the son of English immigrants who wanted him to become a Methodist preach...