How did some of the most savage and desolate islands in the world, scattered across the Pacific and Caribbean, become U.S. territories? The Great Guano Rush describes the fascinating and little-known history of this earliest example of American overseas expansion. 'Guano' (bird droppings) was the 19th century's most important fertilizer and in 1856 Congress, believing that American farmers were being gouged on guano sales by foreign monopolists, authorised...