But that was then. The generals are now fond of assuring us that in this age of guided missile systems and satellite imagery they can bomb targets with accuracy and precision, sending Cruise missiles straight down enemy ventilation shafts from thousands of miles away. Assuming they are right, that modern warfare is a sophisticated electronic pursuit, why does the army still need to fence off so much of Britain and pound it with shells? Why must so many wild open spaces be set aside for target practice with missiles dropped from screaming jets?
Those who are charged with our defence must be allowed to train - but do they really need so much space in which to do so, especially in an age when soldiers are more likely to be acting as peace-keepers, while their generals contemplate a European super army with an entire continent on which to play war games? The trouble is that, as homosexuals and black people have found, getting the British army to agree to change is very difficult - unless it is to do with its demands for money to pay for shiny new weapons.
The army's rigid possessiveness matters, because access to uncultivated land reminds us of our place in nature, and our obligations towards the planet. The population of Britain has multiplied many times since 1918, and our islands are increasingly overcrowded. We are running out of places to wander lonely as a cloud, with the precious exceptions of those parts of Dartmoor, Pembrokeshire and other areas of natural beauty that the MoD guards so jealously. Such areas have a quality that conjures an image - for those few people who have been privileged or daring enough to see them - of what Britain must have been like before the Industrial Revolution.
It is ironic, of course, that in one sense these landscapes owe their wild beauty to the very fact that for decades they have been protected from the despoliation of intensive agriculture by the very guns that also keep the people out. Indeed some environmental experts suggest that dropping the occasional bomb on a landscape is better for wildlife than aggressive farming, or development for housing. Nobody is suggesting that hordes of tourists be allowed to invade the firing ranges, but there must be a case for responsible members of the public to be allowed to walk on, and enjoy, these natural treasures. The MoD warns of unexploded shells, but if its bomb disposal units can clear landmines under the noses of the Khmer Rouge surely they could cope with stretches of Dorset?
So far the MoD's attempts to respond to our changing times have been half-hearted, and, to onlookers, frustrating. The army has a habit of sealing off large areas for manoeuvres that never actually take place. Worse, some sites are hardly used in pursuit of the national defence at all. Thorney Island in West Sussex, for instance, is where military families enjoy a "private" beach and sailing club behind barbed-wire fences.
The recent suggestion that the right to roam will be extended to some military sites at some point in the future is welcome, but experience suggests we should be cautious about MoD promises. In 1943 the army evacuated the village of Tyneham in Dorset, with the pledge that its inhabitants could return to live there once the war was won. That promise was not kept. At the end of a century of war, as we dare hope for peace, it is time the MoD finally kept its word and gave back the land it no longer needs - land that belongs to us all.