ORIGINAL: Merv0728
[GoodGuy],you mention military maps a lot,is it necessary to have military [ones] just for the topographic map making ?
No. Especially if you keep in mind that quite some of them featured a collection of inaccuracies and outdated details.
Example:
The US maps covering the Hürtgen Forest area displayed a route (road) down to and through the Kall valley (Kall gap), which made the US HQ think the "Kall trail" would be a suitable road for supply traffic, and even more important, a suitable route to get tanks to the frontline. The road turned out to be a track only that was too narrow to hold the supply traffic - in a terrain that wasn't a bit tank-friendly, neither the Kall trail itself nor the forest tracks could be used by tanks, maybe except for some rare strips.
Few other vehicles could use the trail, but mortars couldn't be used in these dense woods, and the few clearings that could have been used turned out to be death-traps, as either German arty and MG posts had them zeroed in or they were mined and packed with booby-traps. Guns and supplies had to be manhandled by the infantry, mostly, but Kall trail and forest tracks had been contested by the Germans on various spots, and even the scarce flow of supplies had been interdicted by artillery fire. The Germans had similar problems regarding supplies, but they were the defenders, and they could rely on horses, to some extent.
US Infantry units moving forward in the woods were stopped or slowed down and demoralized by German artillery using air bursts (grenades set to detonate in the air instead of on impact on the ground), delivering an evil amount of flying parts (shrapnels and wood splinters), often rendering them unable to progress due to missing tank/APC support, lack of supplies or heavy weapons. At later stages, in November (the operation started in September) US engineers blasted paths through the woods and rough terrain, to improve the transport problem and to allow for tank support.
US Army sources document that the US 9th division made 3,000 yards into the forest until mid-October at a cost of 4,500 casualties. The 28th US Inf Div., which replaced the 9th on 26th of October, performed probably one of the most costly actions, namely after taking the towns Schmidt and Kommerscheidt, during the German counterattack, which drove the surviving US troops back to Kommerscheidt. In mid-September, the battered 28th had to be pulled out of the frontline, as the unit had over 6,000 men casualties, due to the fact that the Germans committed 3 divisions, where one of them was the 116th Panzer-Division. The Germans needed the Hürtgen "hinterland" for the build-up of the Ardennes offensive. MacDonald states that the US overall loss in the Hürtgenwald area, after the several battles (i.e. "All souls battle" and Operation Queen), amounted to around 32,000 men from September to early December 1944.
Most of the US troops participating in the battle were highly trained, but they were not trained for trench warfare or fighting in woods. In turn, the Germans could draw upon 2-3 years of experience fighting either in similar terrain or under similar conditions in Russia, the Balkans, or Finland (attack towards Murmansk)/Norway.
All that trouble and the massive amount of casualties just because the Allied HQ trusted the map material on hand, although they could have verified it with recon missions. The US thought the Germans in this sector were ready to withdraw and that the roughly 5,000 Germans (initial number) wouldn't put up significant resistance, so they considered this area to be a perfect spot to contest the left flank of the German defenders covering the Aachen and Eifel area.
Quite contrary, the Allies had good map material covering the Overlord area for example, since their aerial recon and the French resistance delivered vital additional infos, but US and UK cartographers couldn't come up with accurate/up-to-date data for quite some Belgian or German regions.
Another example:
Although Allied maps included "Hill 400" in the Hürtgenwald area, the Allies did not consider it to be an important target, and the maps didn't include the bunker installations residing on that hill. The Germans put up staff HQs on that hill, namely the HQs of the 1055. Grenadier-Regiment (89. Inf. Div) and II. Bn/980. Grenadier-Regiment (272. VGD), using bunker installations and observation posts that had been erected as parts of the westwall, so the Allied intelligence didn't rate this as priority target.
But the most important detail here was the fact that a German artillery obs. post was coordinating the artillery missions (a detail unknown to the Allies), as this post could monitor the entire battlefield and probably a third or even more of the entire Hürtgenwald (the Hürtgen forest was a plateau with a size of 140 square-kilometers, covered with dense woods). The US could not pinpoint the location of the German artillery in this sector (some 150 guns in October/November), because the Germans kept shuffling them around, with the observers being the only fixed unit for the whole time. The Germans even put up guns right on or next to the hill on one or another occasion.
US troops didn't attack the hill until December 7th (months after the operation began), after taking the town Bergstein right below the hill, on the 5th. The attack on hill 400 is depicted in a mission in the game "Call of Duty" (Bergstein?).
It seems like US troops thought the Germans would just use the hill as AA strongpoint and like US HQs initially considered the installations on the hill to be a rather useless set of ancient ruins (remains of a castle) and AA guns.
That said, military maps aren't necessarily more detailed (as they often left out details - as explained above), nor do they always contain topographical info.
But if they contain topo infos, it's the easiest way, as you just have to "paint out" contour lines of the map underlay with COTA's height layers and road lines.
I'd recommend that you try to get some historical road maps OR actual maps (ebay, internet, library books) covering your area of interest, in case you can't get military maps.
The next steps then are:
- to use Google Earth as base for the topographical details.
You can prepare (means cut) map scans/images in a DTP program, and then put the map parts in Google earth as overlay (with like 20-30% transparency) ... using almost the same technique which is being used for the underlay function in COTA's map maker. An overlay in Google can be used to double check or gather the terrain layout.
You basically just match the road map and the 3D-terrain in google earth. All maps usually contain captions explaining the scale, so you just have to make sure that one kilometer on a given map matches 1 grid square (= 1 km) in COTA, when taking the maps or screenshots from Google Earth as underlay.
- to move the mouse pointer over any given point, which should give you a halfway accurate height info in the status bar (in meters or feet)
Another excellent way of getting infos about hill formations is to use Google maps and switch to "terrain" instead of maps. Google maps provides a pretty accurate 2D top-view that way, helping to identify ridges, plains, plateaus and coast-lines, a great way to understand and accurately render the terrain. Then you can just use Google Earth to get the height values.