Where these were a long way away then the FPF would be located on the likely assault route between the FUP and their own loc.
That is correct. But a point on the slope in front of the crest of a hill, for example, so that attackers running downhill would have to cross the arty barrage, or a strip of open terrain with some distance to the edge of a forest (where the FUP was a point inside or behind the forest) - and not the edge of such forest, as that would give the attackers the opportunity to abort and get to cover (foxholes, trenches), offered more opportunities to increase casualties on the enemy side.
The reason for trying to locate it on the FUP is that it gave you the most time to hammer the opponent.
In practice, for the Germans, arty fire could not be observed - quite often, when it came to distant target locations, that goes especially for German attempts to bombard crossroads and supply routes in Allied sectors during the Ardennes offensive, where such bombardments were often less effective, or even completely off-target (with 0 effect), despite the use of halfway decent matrices, as corrective measures were not at hand.
In the Ardennes, unlike in France, distant/obstructed (means there were hills, woods or other terrain features/defensive measures that denied observed fire) FUPs were rarely bombarded, and Allied troops had often moved on/attacked already, once coordinates of FUPs had been finally figured. In the main, the Germans focused on enemies who could be observed and who offered worthy targets (in times where some non-Ardennes sectors on the Western Front were not allowed to spend more than 7-10 shells per day), as the supply situation deteriorated.
There were more reasons for the relatively low amount of unobserved fire on FUPs in the Ardennes, one reason was the lack of aerial recon (only short-range Fieseler Storch recon planes were sent here and there), another reason was that German forward observers on the ground could rarely penetrate or bypass defensive perimeters. In turn, US observers got cut off a few times (and even surrounded inside villages), or managed to penetrate German lines, which allowed them to give accurate directions for bombardments. One time a forming distant German tank group got shelled that way, if I am not mistaken.
In turn, in the Huertgen Forest, in the areas with those really large forests, a myriad of German bombardment missions targeted US troops deep inside the woods, also executed by single guns or small group of mortars and 75-mm infantry guns.
There's a famous picture of a 150-mm s.IG 33 (heavy infantry gun) hammering US units during one of their numerous attacks (see below).
The gun had been hauled deep inside the forest, and the crew set it up at the edge of a small clearing, perfectly concealed/protected from aerial bombardments. In front of the gun and next to the gun, you can see branches which were used to camo' up, if the gun didn't fire. If you check out the angle of the gun and if you check the angle/alignment of the trees, then it looks like the elevation is not set for max range (trajectory may be a tick too flat):
Some bombardment units created their own clearings, there are also pictures showing mortars performing regular and ultra-high angle bombardments, all firing from positions deep inside the woods (clearings, or sometimes engineers just cut one or another tree and climbed up and cut the treetops of the surrounding trees, which was sufficient for high-angle mortar fire) .
As during the Huertgen-Forest campaign (5 months) the whereabouts of most of the US troops in the woods were halfway (or even well-)known, the Germans performed both, unobserved and observed fire. Since many positions and even some villages changed hands several times, quite some guns remained zero'ed.
The battles in the Huertgen Forest (coined "Hurtgen", from "to hurt") were particularly bloody, one reason was the heavy use of artillery airbursts in the wooded terrain, responsible for a lot of the US casualties in that campaign.
If these were not possible then they opted for the first visible location along the likely assault route - eg the crest of the hill. Once called in the caller would then drop the range so the fire could track the enemy's progress along their assault route and this often led to the fire being called in very close to the friendly positions. But it usually began from a registered position further away.
That's correct and that matches what I outlined here and in my previous post. Registered points were not establishd in front of a unit's toes, of course. They were established ahead of a friendly position, probably 200-400 meters (if the terrain was complex/dense), but could be shifted (reduced or increased) easily, once the fire was registered.
But in locations where approach routes were short, eg. a short strip of open terrain between a forest occupied by the Allies and a village occupied by the Germans, or like in the Huertgen Forest area - where one half of one or another Village was occupied by the Germans and the other half by US units), fire was ordered immediately and corrected by an OBS "on the fly". Risky, but necessary, quite often.
So, what's the minimum distance allowed in the game (with "avoid friendly fire" unchecked)?
