In 1890, US naval officer Alfred Thayer Mahan published The Influence of Sea Power upon History, 1660-1783, an essay destined to revolutionise world strategic thinking. Mahan's thesis was as simple as it was disruptive: a nation's supremacy was based on its control of the seas and oceans. According to Mahan, the great powers of the past - particularly England from the age of Elizabeth I onwards - had achieved hegemony through their sea power, understood not only as military power, but also as commercial, infrastructural and logistical capacity. By sea power Mahan meant not only the ability to maintain and renew a war fleet, but a complex and interconnected system that included ports, safe trade routes, a merchant navy and a nation cohesive in supporting them. Mahan dwelled mainly on the period between the 17th and 18th centuries, a period in which England, using its fleet and favourable geographic location, had been able to dominate global trade, defeat continental rivals and create a "maritime" empire of unprecedented proportions. In fact, being an island entailed two major geopolitical advantages: the first was the ability to project itself onto the sea; the second was the ease of defence, as the defence of maritime borders greatly reduced the risk of invasion. Mahan's theories profoundly influenced the naval strategies of the United States, Japan and the European powers, fuelling the naval arms race that culminated in the world wars of the 20th century. Mahan was an extremely influential thinker, read and studied by leaders such as US President Theodore Roosevelt, German Admiral Alfred von Tirpitz and even Japanese Admiral Isoroku Yamamoto.