A natural border is a border between states which are composed of natural objects such as rivers, mountain ranges, or deserts. Border stone at Passo San Giacomo between Val Formazza in Italy and Val Bedretto in Switzerland Borders define geographic boundaries of political entities or legal jurisdictions, such as governments, states or subnational administrative divisions. ... A state is an organized political community occupying a definite territory, having an organized government, and possessing internal and external sovereignty. ... The Murray River in Australia. ... The most general definition of a mountain range is a group of mountains bordered by lowlands. ... A dune in the Egyptian desert In geography, a desert is a landscape form or region that receives little precipitation - less than 250 mm (10 in) per year. ...

Having a natural border is strategically very useful, as invading armies have a hard time crossing such a border. They are also easily defended. A strategy is a long term plan of action designed to achieve a particular goal, as differentiated from tactics or immediate actions with resources at hand. ... Army (from French armée) can, in some countries, refer to any armed force. ... In military science, defense (or defence) is the art of preventing an enemy from conquering territory. ...

Expanding until natural borders are reached, and maintaining those borders once conquered, have long been major foreign policy and war goals in the past. For example, the Roman Republic, and later, the Roman Empire expanded continuously until it reached its natural borders: First the Alps, later the Rhine river, the Danube river, the Sahara desert, and others. From the Middle Ages onwards until the Industrial Revolution, France sought to expand its borders towards the Alps, the Pyrenees, and the Rhine River, while gradually releasing any territories held on the far side of those borders, because they were difficult to hold successfully in the long run. For the American magazine, see Foreign Policy. ... An act of war - the atomic bombing of Nagasaki, Japan on August 9, 1945, effectively ending World War II. The bombs over Hiroshima (August 6) and Nagasaki immediately killed over 120,000 people. ... See also Roman Republic (18th century) and Roman Republic (19th century). ... The Roman Empire is the term conventionally used to describe the Ancient Roman polity in the centuries following its reorganization under the leadership of Octavian (better known as Augustus). ... The West face of the Petit Dru above the Chamonix valley near the Mer de Glace. ... At 1,320 kilometres (820 miles) and an average discharge of more than 2,000 cubic meters per second, the Rhine (German Rhein, French Rhin, Dutch Rijn, Romansch: Rein, Italian: Reno) is one of the longest and most important rivers in Europe. ... The Danube (German: , Slovak: Dunaj, Hungarian: , Croatian: Dunav, Serbian: Дунав/Dunav, Bulgarian: Дунав, Romanian: , Ukrainian: , Latin: Danuvius) is Europes second-longest river (after the Volga). ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... The Industrial Revolution was the major technological, socioeconomic and cultural change in the late 18th and early 19th century resulting from the replacement of an economy based on manual labour to one dominated by industry and machine manufacture. ... Central Pyrenees The Pyrenees (French: Pyrénées; Spanish: Pirineos; Occitan: Pirenèus or Pirenèas; Catalan Pirineus; Aragonese: Perinés; Basque: Pirinioak) are a range of mountains in southwest Europe that form a natural border between France and Spain. ...