Above the Trenches
Design Essays

Bloody April: Combat Resolution

So let's put up the British 3xF2, 2xR0, B0 in the Arras area against the German F3, F2 fighter patrol and see what happens.

If we're going to recreate the historical tactics, each side needs three deployment zones in each map area:

• Across the Lines
• Above the Trenches
• Behind the Lines

Of course, a German unit in the German "Behind the Lines" zone and an Allied unit in the Allied "Across the Lines" zones are in the same physical airspace:

In addition to combat effects, a unit's location will affect what kind of mission it performs, the victory points that it can earn, and how easily replaced it will be if shot down. But those are topics for further essays.

The British deployment is best recreated with 3xF2 going "Over the Lines" for their offensive patrols with the 2xR0 going "Above the Trenches" to represent their artillery spotting and contact patrol work. The B0 is still a bit up in the air and might in fact end up as an R0 instead; in either case it goes "Over the Lines" to represent long range bombing and recce work.

The Germans deploy both Jagdgeschwaders "Behind the Lines".

To recreate the point of the British offensive patrols, we'll let use the following combat sequence:

1. Friendly Fighters "Over the Lines" fight; casualties come from enemy "Behind the Lines" and then "Above the Trenches"
2. Enemy Fighters "Behind the Lines" fight; casualties come from friendly "Above the Trenches" and/or "Over the Lines" per enemy decision

Casualties always get to fire at their attackers before being removed.

So we begin with 3 British F2s shooting at the German fighters. By reference to their combat values we see that each has a 20% chance of inflicting 2 casualty points (CP) and a 10% chance of inflicting 2 kill points (KP).

But we've got three units firing, so the math to compute the results gets a little hairy. That's a great excuse to do some programming (not that I need much excuse). I end up with the following probability chart:

'C#' means # CPs, likewise 'K#' means # KPs.

Originally I had thought that K points forced elimination of at least that many points, while C points drove off (no further combat) for up to but not over that many points of units.

But consider the case of a Fokker E.III wing (F1, 2 damage points) up against a SPAD 13 Escadre (F4, 3 damage points). With the above rules, the Fokker has a 10% chance of eliminating the SPAD but no chance at all of driving it off.

That sounds backwards to me, so let's make K points as "not to be exceeded" and C points as "at least this many". Now the E.III has a 10% chance of driving off the SPAD via a C2 result, and its K2 result (a 10% chance) has no effect.

The Germans have an F3 with 3 damage points and an F2 with 2 damage points, so the above results boil down to:

Even with casualties being able to shoot back at their attackers, these results actually seem a bit generous to the British in light of the historical results. There's about a 20% chance that the fighter sweep will completely protect the recce planes above the trenches, there's a greater than 60% chance that at least one Jagdgeschwader won't get through.

As a comparison, if the Germans are assumed to have 2xF3 instead of F3, F2, then the results look like this:

That is more reasonable, and it's not farfetched to assume that the Germans would group up their best planes in an area where an offensive is occurring. It still seems to overstate the effectiveness of the British, though. Either my OoB analysis is off (and there's at least one explanation there in that I didn't account for green British pilots), or my proposed combat values understate the differences between aircraft generations. Possibly both reasons are showing up here.

With two F3s, the German return fire as follows

There are two British R0s (1 damage point) Above the Trenches and with the above results they are either completely unscathed or both are casualties. And this is the best case for the Germans, where both Jagdgeschwaders get their shots in. This is just far too coarse-grained.

So it's time to do some slight retooling of the counters' combat values and damage resolution.

(And if this all seems a little non-detailed, remember that we're going to be doing this procedure in each of seven areas over twelve turns. We can't spend too long resolving combat in any one particular area or the game will bog down.)