Hugh Westacott wrote: “But your explanation has made me understand that contours in lowland countryside would be vitally important to a soldier who had to cross enemy territory without being observed.”Well Mr Westacott, you are absolutely right and I am not entirely right; allow me to elucidate.
Soldiers need to move with concealment, frequently with features in the landscape which have changed, even completely disappeared.
Buildings, even entire villages and towns can be completely obliterated off the map. Cities such as Hiroshima and Nagasaki had vast areas of population simply wiped off the face of the planet.
The destruction of war changes many things, yet fascinatingly, has little impact upon the topography of the ground with the exceptions of munitions such as bombs and mines – a mine is only a buried bomb.
Yet bomb craters are distinct and easily identifiable: during the conflict the earth is freshly exposed and the stench of the explosives can linger for months after the detonation. Even years afterwards, with examples from the fields of Flanders during WWI, their shape is so distinctive they can be easily identified.
Also they are relatively small. One of the largest non-nuclear explosions in history and the largest ever to occur on UK soil occurred at 11:11am on Monday, 27 November 1944 at the RAF Fauld underground munitions storage depot where an estimated 4,000 tonnes of high-explosives detonated.
This ordnance was stored deep underground, deeper than a bomb would penetrate, yet the crater formed from this massive explosion was only on average 240m in diameter.
Even a thermonuclear weapon makes little change to land topography, primarily because to maximize the range of blast destruction (the pressure wave which radiates from the explosion) thermonuclear weapons are air burst detonition and these produce only shallow craters (mainly created by compression of the soil). The underlying topography of the land is compressed yet looks the same as before detonation.
A military route card looks very different to those we use recreationally, for those interested this is the one I instruct:
Estimated Travel time
Estimated Distance to Travel
Manoeuver room required
Trafficability
Load-bearing capacities of the ground to be covered
Tactical aspects of terrain – observation and fields of fire, cover and concealment, avenues of approach, protection from incoming enemy fire etc.
Ease of logistical support, such as MedeVac
Potential for surprising the enemy
Availability of control and coordination features
Availability of good checkpoints and steering marks
Energy expenditure by troops
Noise created in moving across the terrain
Contours are the mainstay of military navigation and augmented by features in the landscape which are unlikely to change in diminishing order, so starting with rivers and ending with paths.
However, in recreational navigation, boundaries, rights of way, trail signs, are of equal and sometimes greater importance than contours, particularly in lowland areas such as the Norfolk Fens.
I did not make this clear in the UNM Hugh and you are perfectly correct to point this out.