M.S. Anderson 
Rise of Modern Diplomacy 1450 – 1919 [PDF ebook] 

Though international relations and the rise and fall of European states are widely studied, little is available to students and non-specialists on the origins, development and operation of the diplomatic system through which these relations were conducted and regulated. Similarly neglected are the larger ideas and aspirations of international diplomacy that gradually emerged from its immediate functions.This impressive survey, written by one of our most experienced international historians, and covering the 500 years in which European diplomacy was largely a world to itself, triumphantly fills that gap.