The aim of this book is to present in a simple form the long history of the Marina Militare (Italian Navy) both to casual readers and dedicated naval historians. It deals with aspects related to the Italian Sea Power from origins to the end of World War II. Like most institutions, the Italian Navy evolved, grew and changed to meet new circumstances over a long period of time, more than 2,500 years. Its main concern has been the defence of the country and of the overseas territories which in different periods formed part of many Empires, from Rome to Genoa, Venice and so on until today, when the Navy's first priority is national de-fence against the growing threat of terrorism looming over regional security and the economic interdependence of our globalized world. The Archives of the Italian Navy Historical Branch contain unique historical documents little or never used in researches by English-speaking scholars, including many substantial dossiers concerning the World Wars. We are confident that this book, written by two authors of international renown, may be interesting and easily appreciated by all who whish to learn more about Italian naval history. The survey illustrates the evolution of the Italian Navy through its many technological advances. This book intends to be a first essay in English language about the Italian Sea Power. The Italian Navy Historical Branch hopes it will spur other English-spea-king researchers to investigate these themes in depth and publish new studies which may help to propose our maritime history and culture at international level. The statements and views expressed herein are the sole responsibility of the Authors and do not necessarily reflect the official position of the Italian Navy.The Italian Navy Historical Branch is pleased to present this new edition of Sea Power. The book, compared to the previous version, has been enriched by further historical information and a renewed iconography. We confide that this new edition will be a point of reference for those interested about the Italian naval history.