The map could be used as both a competetive and a public one. Since my idea with it is to have a map that recreates the scen of the battle of Waterloo 1815, it will contain the "villages" of Hougomont, La Haye Sainte and Papelotte. (Maybe a few more like: La Belle Alliance, Plancenoit etc.) These villages will make up the three key points of the map, and will therefore be the key to succes. But in general I would've suggested making it more of a competetive map since the big field is also a big part of the battlefield. To make room for all the villages it's also important to make it a big map which suits line-battle maps better. In a public perspective it could still be used in a army conquest though as the three villages as capture points. Here we could also have three different spawn points and threfore making it a 2 vs 1 scenario. The French might start at "La Belle Alliance, the British behind the big ridge in a camp looking facility and the Prussians spawning from the east.
As said before the villages will be a key factor in a public sence whilst a competitive point of view will probably use up more geographical features. Therefore I would've recomended adding walls, and patches of trees to the map. The big ridge where the british were originally placed would also be a big factor in the battle as in real life. (Of course keeping in mind the historical accuracy).
If the map would be in true scale the map would obviously be to big. Therefore you would've wanted to scale it down. The question then is how much. In this youtube clip linked (coming from the game mount and blade) the down scaling is resonable. This means that you can travel from one side of the map to another pretty fast while still not having the "villages" taking up to much space.
The enviroment will be very open and flat with some features here and there. For example stone walls, trees, wagons, fences etc. For seeing the enviroment even better I would refer to google maps.
Maps from the battle: http://www.napoleonguide.com/maps_hmwater1.htmhttp://www.emersonkent.com/map_archive/waterloo.htm