A two pronged study of, one, how generals learned the country over which they fought, and two, how campaigns are explained in military history.
Any means to hand that helps. Maps most of all, but guides, books, and just plain first hand experience as well.
The map is not the ground. Still humans are visual creatures, and a successful general needs to know a lot about places, their names, how far they are from each other, and how they're connected. It's all information best presented in a graphic format. By means of maps.
What we know of Napoleon's methods during his years as Emperor indicates he valued them highly. Elting writes that Napoleon's Staff, the Etat-Major General included a "Service Topgraphique, responsible for the army's map supply and for topographical reconnaissance, terrain studies, and map making. It was accompanided by a mobile printing shop and a small copper plate press, the first used to publish orders of the day and bulletins, the second for the preparation of rough maps based on both existing maps and recent surveys."
As Elting writes elsewhere of it the key individual in this branch was Bacler d'Albe. To quote from elsewhere: "Finally there was the Topographic Bureau with its extensive collection of maps, fortress plans, and notes on the 'resources' of the area, headed by Chef d'Escadron Louis Bacler d'Albe who maintained Napoleon's situation map."
The Osprey book on Napoleon's HQ by Ronald Pawly describes how Napoleon made use of these maps: "Before opening any campaign or battle, the Emperor shut himself up with Bacler d'Albe in the topographical office, where they would examine maps glued on linen or cardboard, measuring, estimating and calculating distances; coloured pins planted in the maps indicated the various French and enemy units. From time to time the size of the maps obliged both men to climb on to the table; lying stretched out on it they were sometimes so absorbed that their heads came into collission ... Bacler d'Albe's office may be considered as the origin of all initial campaign planning; once Napoleon had decided upon a general idea of how to move his troops, he would call for Marshal Berthier and dictate his instructions." Pawly goes on to write just a little later " While on campaign Bacler d'Albe was the second most important man in the Imperial Headquarters, and was always the first and last to be consulted by the Emperor before leaving, whether by day or night."
Maps though, especially those of that period, have their limitations. Again to quote Elting: "Maps are an absolute necessity to a commander for both the planning and conduct of operations. At this perod, however, the scientific mapping of Europe had barely begun; few large-scale maps were available, and none had an accurate relief system to show variations in elevation. Consequently, the Grande Armee had to use foregn maps, which were frequently unsatisfactory and always in short supply, or make its own."
As a result especially during the Revolutionary period commanders had to use other methods to learn the lay of the land. Personal familiarity, reconnaisance by scouts and senior aides, and guides all played prominent roles.
If maps weren't everything to be hoped for during the imperial period they were even more deficient during the revolutionary wars. Generals had to depend heavily on their own knowledge of the country or find guides.
One the of the advantages both Bonaparte and Massena had at the beginning of the Italian campaign of 1796 was that they were both of Italian background and had spent several years prior in the initial area of operations getting to know the terrain in detail.
One example of a general not knowing an area they were operating in sufficently being a problem was Vaubois in the Tyrol. He'd performed well in earlier roles but was insufficently familar with the Adige valley to know the key points there. As a result he ended up being replaced by Joubert.
An example of the problems that could result from the use of guides was Massena's effort to cut off Wurmser who was making a break for Mantua in September of 1796. Massena in hot pursuit managed to cross the Adige at Ronco upstream of Wurmser at Legnago. He wanted to march south-west cross country on secondary roads to cut off Wurmser from Mantua somewhere on the road between Cerea and Castel d'Ario. His local guide instead took him along a road that mostly followed the river. In the event the forces he got in place to stop Wurmser were too few too late to do the job.
Maps are not only useful, but with conditions, for generals on campaign they're also useful for those later trying to understand those campaigns.
Professionals sometimes maybe, but often just interested amateurs, armchair generals.
In these cases maps have to do triple duty. They not only have to convey the sort of information the actual commanders would have needed from their maps, they have to convey information the commanders on the spot would have known as a matter of course, and they have to convey the sequence of events and to some degree the decisions those events occassioned.
Historical, after the fact, maps have a burden of familiarization to places and periods comtemporary ones didn't. They also have to aid in the reconstruction of events that those on the ground experienced as they occurred. In truth those examining events after the fact are often attempting an overall level of understanding denied those who had to experience them as they occurred. This all the better to use them as object lessons.
Games have to show all the places that mattered historically, plus those that might become so in the alternate history a particular game might end up showing. They have to also show all terrain features that might matter and be useful for regulating movement. They have to do so in a fashion that retains an easy usability. It requires a drastic winnowing of what information to present.
Computer games somewhat solve the movement control problem, conventionally solved to an acceptable degree in boardgames by hexfield maps, but they have given historic problems with resolution had even worse problems with scale and adequate selection of detail.
Computer games usually have at least two main scales a strategic or campaign one, and a tactical one. Even the tactical maps tend to show areas too large for men and units to appear clearly at original scale and therefore resort to the device pioneered by minaturists of blowing multiple small men up into a single large figure. Perhaps as computing devices grow in power this problem will resolve itself.
Information and its manipulation are the hallmarks of our age.
That doesn't mean we do it well, or show much historical or geographical insight in the process.
It maybe that progress in the development of hardware is slowing down. It may also be that increased social regulation of technologies that have shown themselves vulnerable to abuse will be a further restraint. Just the same I believe that there's a lot of room for improvement in software for this field.
Our current use of computers in understanding military history has a lot in common with a dancing bear. It's not that the bear dances well it that it dances at all. Currently much of what is seen on computer screens is in spirit a porting of earlier technologies, virtual hexfield board games, or virtual tin soldiers.
An issue is that with the proliferation of devices comes a fragmentation of possible markets. There is a common illusion that software is easy and cheap, in fact, it requires the devotion of highly skilled people for prolonged periods to produce often uncertain results. This is costly even though the end user may not appear to pay much.
For the consumer great simulation software, especially that devoted more to understanding than thrills, will likely only appear slowly and over time.
Professionals have other problems. Some obvious ones are that large bureaucratic organizations tend to have more problems with software than smaller informal teams do. Computers are magnifiers, they magnify bureaucratic inefficency quite well. Also as convenient as fully informing soldiers and commanders via the electronic battlefield against technically competant opponents security issues are likely to be a problem. Software is notoriously hard to properly secure.
A defence is only as good as its weakest link and software has many links.
The first goal of maps on this web site is show where places are. A close second is to show where particular units were at certain times. Ideally some idea of the terrain, mountains and rivers in particular will be given. In doing this the fact that these maps will be shown on a wide variety of devices with different sizes and resolutions has to be accounted for. Symbols and lines that don't scale well have to be avoided. Lines and symbols in fact are best avoided entirely. Floating areas of color for elevation work much better than contour lines for instance. Where lines and symbols (including text) can not be avoided as for place names, rivers, and roads, they have to be made simple and rather large so they show up on small low resolution devices as well as on big desktop screens.
In a modern context the esquisitely detailed maps composed of many fine lines, but likely in monochrome, found in the best 19th and 20th century atlases and books don't work so well. Something with less detail, and that less fine, but using color is likely to work better. What works best is still something I'm working on.
It's hard to do the question of commanders being able to access the information they need full justice.
Maps are very useful. Good maps weren't available for most of history, that was just changing in the Napoleonic period. Even when you have good maps they have their limitations.
Armchair generals of whatever persuasion are likely to have better maps than the historical generals did. Unfortunately those maps have a lot more to do.
Computers hold the promise of helping some with these problems. It's a promise yet to be realized, and there will be real fundamental issues to be resolved in doing so.