08 December 2010

How far can you see and know what you are seeing

It's not hard to find guidance on the distances at which troops can be seen. For example, this nice little table from the Kriegsspiel website. Problem is, there are two factors that make such figures of limited use.
  1. They don't take commonplace optics into account -- officers frequently had a set of binoculars. Modern (well, WWI) optical range finders were not yet in use, so you don't have a lot of help in ranging for artillery fire, but you can get a grip on the presence and nature of a body of men at a far longer range.
  2. What really interferes with visibility is not distance, but the clutter between the observer and the potential observable.
So, how do we take this into account. Well, first, for the sake of argument lets set an upper limit for observation, say 3km - that will be 12" on the table. That will be to see formed, concentrated troops.

Now, lets limit that. Lets divide the world into flat and slope. That's more than a bit artificial, since the world is just not that flat. But our wargames tables are and that is what we have to work with. We'll also divide the world into levels, to lend some meaning to our hills. We won't worry right now about what sort of height difference we mean.

The point here is that, if you are in a hill or a slope and what you are trying to see is on a lower level or a slope facing you, you will able to see some over proportion of obstructions. Likewise if you are in a town with a convenient church steeple.

On the other hand, while you can see a regiment in column of companies easily enough, men in an extended line who are taking advantage of the terrain will be far harder to see. Unless they are shooting at you; there is no smokeless powder in this war.

So how does this turn into rules? I'm not sure yet, this is just where my thinking is right now.


  1. Are you sure that the sighting table doesn't take into account telescopes? (granted 1870 field glasses might be more powerful) It at least consisders someone with better eyesight than me.

    3km for a man standing up on flat ground is pretty much the full distance to the horizon. A mounted man/officer can see a bit farther about 5km I think. Again with no obstructions.

    When i climb the low hill across the road I can see varying distances but only certain isolated spots at a distance are visible even at a km or 2 with dead ground between me and them but then I am in hilly terrain with a wooded patches.

    Visibility from the bridge of a destroyer was better on a clear day. (another factor humidity also affects it)

    Then there is recognition...

    This almost calls for some kind of field test vs measured distances.

  2. Yes, I am really thinking of 3km as the extreme best case; large bodies identified enough to take the blind off, but not really for effective fire. And at that only in an ideal case where the observer has an good, elevated position with the enemy on the plain below. Which was a feature of the positions magnifique which were the basis of the "plan" for frontier defense.

    I think the battlefields should be quite broken; not so much from a movement perspective as from a visibility perspective.

    However, I have a couple of interesting images - gotta love google earth -- which won't go in a comment so I'll do a post