Cartographic censorship is the deliberate modification of publicly available maps in order to disguise, remove, or obfuscate potentially strategic locations or buildings, such as military bases, power plants or transmitters.
[3] In October 1941, before the United States entered World War II, President Franklin D. Roosevelt announced that he had "a secret map" of South America titled "Luftverkehrsnetz der Vereinigten Staaten Süd-Amerikas Hauptlinien".
[4] In the Age of Discovery there was a premium on geographic information: ports of call for wood and fresh water, deep natural harbours, shorter passages and straits.
It complained when ships owned by its rival, the Australische Compagnie, entered the Pacific by a new passage round Cape Horn, named the Le Maire Strait.
[5] The German cartographer Henricus Martellus made his famous mappamundi (World Map), soon after the Portuguese navigator, Bartolomeu Dias, sailed round the southern tip of Africa.
His purpose was to pretend that the new eastern sea route to Asia and was far longer than it actually is, in order to discourage foreign interlopers from profiting from Portuguese discoveries.
Its purpose, according to Engel, was to exaggerate the length and difficulty of the Northeast Passage along the arctic coast, in the hope of discouraging rival European merchants from attempting this route to the Pacific and China.
The British Admiralty sent James Cook on his three Pacific voyages during the Second Hundred Years War when France and Britain were vying for commercial supremacy and control of shipping lanes around the world.
Cook has been accused of making "major mistakes in his charting", such as depicting "Stewart Island as a peninsula, and the failure to determine the insular character of Tasmania".
[10] In the United Kingdom, during the Cold War period and shortly after, a number of military installations (including "prohibited places") did not appear on commercially issued Ordnance Survey mapping.
[citation needed] Lists of air traffic obstacles may not be published by many countries as many of them are strategically important (chimneys of power stations, radio masts, etc.)