Monroe, McKinley, Wilson, G. H. W. Bush: Modern statesmen seek to fashion a new order in the world, while Americans debate their role in it. A president's greatest is to represent the nation to the world, and securing a stable world in which American interests can be defended has long been a basic tenet for him. These four men took on the task at critical times in U.S. history, with international achievements their most durable legacies.