There are significant differences among POW camps, internment camps, and military prisons. Purpose-built prisoner-of-war camps appeared at Norman Cross in England in 1797 during the French Revolutionary Wars and HM Prison Dartmoor, constructed during the Napoleonic Wars, and they have been in use in all the main conflicts of the last 200 years. The main camps are used for marines, sailors, soldiers, and more recently, airmen of an enemy power who have been captured by a belligerent power during or immediately after an armed conflict. Civilians, such as merchant mariners and war correspondents, have also been imprisoned in some conflicts. With the adoption of the Geneva Convention on the Prisoners of War in 1929, later superseded by the Third Geneva Convention, prisoner-of-war camps have been required to be open to inspection by authorized representatives of a neutral power. Not all belligerents have consistently applied the convention in all conflicts.