A prisoner-of-war camp is a site for the containment of enemy combatants captured by a belligerent power in time of war. It is similar to an internment camp which is used for civilians. Purpose built prisoner-of-war camps appeared at Norman Cross in England in 1797 and HM Prison Dartmoor, both 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 soldiers, sailors, marines, coast guards, and more recently, airmen of an enemy power who have been captured by a belligerent power during or immediately after an armed conflict. In addition, non-combatants, such as merchant mariners and civilian aircrews, have been imprisoned in some conflicts. With the adoption of the Geneva Convention on the Prisoners of War in 1929 and later superseded by the Third Geneva Convention, prisoner of war camps have been required to be open to inspection by authorized representatives of a neutral power.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.