Summary: When the Vikings invaded and conquered England, France, and Ireland, it opened a new and fascinating chapter in the era of the Norsemen. The nature and history of the beset lands, the traditions and character of their peoples, and the strengths and weaknesses of the various Viking leaders made each of these three invasions distinct from the others. And each produced a different and surprising result. In sum, award-winning journalist Robert Wernick asserts in this short-form book, they forever altered the course of medieval history