The Miracle on the Marne
The first world war began at a lightning pace. Per the Schlieffen-Moltke plan, Germany sought to defeat France before Russia could fully mobilize (the assumption that Russia’s concentration of forces would be sluggish proved to be overly optimistic, in part due to French rail investments in Russia), which it would do by avoiding the French fort system along the Franco-German border, by invading Luxembourg and Belgium. The majority of German forces were to amass in the West, surround Paris, decisively remove France from the war, before turning east to deal with Russia. This defeat had to be achieved in 6 weeks.
In 10 days, the fortress city of Liège had fallen to Germany. In 20, Antwerp was besieged - it would be surrendered 2 weeks later. In this short time, the French army had retreated from defeat at Charleroi and Mons, falling back into France itself. On the 25th day of the invasion, the German 1st Army approached Meaux, the doorstep of Paris.
At that moment, while the French government were preparing to evacuate to Bordeaux and Parisian taxicabs were ferrying troops to the looming front, a gap opened in the German lines, and the French and British were able to counterattack. This was the ‘Miracle on the Marne’.
After a modest German retreat behind the Aisne and the Somme, each side dug in for good and the front of the next four years ossified.
Why the WWI Mod Needs a Marne
The incursion of Germany into northern France - with all that it entails - followed almost inexplicably by a completely stagnant war of attrition, is such a familiar feature of the First World War that I knew I’d have to deliver it from the start of my project. Though a clever Belgium player may be able to halt the Germans at Liege, or a crafty France player may even be able to achieve a reverse-Marne into Germany, the default campaign should see this initial German success falling just short of Paris.
Hearts of Iron IV’s battle mechanics do not at all suit this sudden transition. In vanilla, World War II HoI4, armies generally move at a quick pace, but not one resembling the flank-oriented routing of early Schlieffen. While the front can grind to a halt, it generally signifies two equally sized armies, one of which (usually the Axis) will tend to atrit faster than the other. HoI4 tells the story of the war through quick-to-mobilize fascist nations scoring explosive victories against the slower, but ultimately stronger Allies. The tides turn in years, not months.
An existing WWI mod - the very impressive Great War mod created by Wolferos and maintained by another team - has to pull some rabits out of its hat to achieve the Miracle on the Marne. Rather than relying on the gradual evolution of battle mechanics, it uses a bespoke bonus for Germany to enable a quick push. A skilled player can rush to Paris before it gets removed in two months.
One of my motivations for creating this mod was actually a dislike of this approach. I felt from the very start that the Marne represented a progression of battle doctrine, and HoI4 already has a mechanical system for exactly that.
Battle doctrines represent changes in the way an army fights tactically, rather than technologically. Vanilla HoI4 has 4 of them, broadly representing the German (Blitzkrieg), American (mass artillery), British (post-trench warfare), and Soviet (defense in depth/large army) dogmas that emerged in the 2nd World War.
You pick exactly one of these at the very start of a campaign, which on one hand lightens the decision-making but on the other hand removes any chance of being creative with your doctrine ‘build’. I decided I wanted a doctrine tree which you could freely explore, mixing and maching bonuses. I’ve yet to implement this idea, however: it may prove impossible to balance. But here’s the rough design:
Overwhelm (Early Russian): Opreational war or ‘Operatika’, broad-front attacks, waves of assault. An element of numerical superiority, but this shouldn’t be the end-all. Doctrines seen in the Brusilov offensive.
Surprise (Early British): Quick, unexpected attacks. Successful, but only enough to take the next village. ‘Bite and hold’, supported by extensive artillery plans. Doctrines seen as Britain attempted to break the stalemate through Ypres and the Somme.
Overpower (Early German): The German doctrines of the early and mid war that saw so much success in both west and east. Excellent use of indirect, long-range artillery to disable enemy defenses or to cripple their attacks. Exnetsive use of machine-guns to overcome a numerical disadvantage. Potentially early infiltration/squad tactics.
Endure (Early French): Also arguably Italian: Spalatte (‘nibbling away at them’), the Noria reserve system, and French motorization seen as early as the Parisian taxicabs, but more maturely at the Voie Sacrée outside Verdun,. The doctrines developed at the steady defense of Verdun itself.
These doctrines then reach intermediate ‘switcher’ doctrines, after which you can jump tree to one of the following.
Annihilate (Late Russian, Soviet): Disrupting the enemy deep into its rear, reducing its capacity to entrench or counterattack. Exploit defensive failure with highly mobile units. The doctrines of Soviet (originally, Russian Imperial, like so many Red generals) Vladimir Triandafillov.
Cooperate (Late British): Combined arms, particularly tanks, in addition to sappers. The British tactics of Cambrai and St. Quintin that saw trickling gains that were to eventually break the German grip.
Infiltrate (Late German): Squad tactics, autonomous troops, swift infantry gains in the east and effective counterattacks in the west. Supplemented with a tremendous ‘three line defense’, the best entrenchment buff in the mod. The doctrines of the march east and the Spring Offensive.
??? (Late French): More research needed!
These doctrines will gradually restore your army’s offensive ability, very slowly breaking the stalemate as did historically.
However, these all come after 1914. The actual transformative change occurs before then, in the early doctrine tree.
The first four doctrines - Early Reform, Pragmatic Uniform, Free Fire, and Indirect Artillery, represent the shift between 19th century formation warfare and 20th century infantry squads. This transition had already begun in the pre-war years: most countries had moved away from coloured uniform, though some decorations like the Pickelhaub and, infamously, France’s pantalon rouge, had yet to be abandoned. Shooting artillery without line-of-sight was not yet the norm; again, France relied heavily on older field artillery. Allowing your troops to move and shoot freely was not yet adopted.
The early doctrines are cheap. Note that all four are needed for Digging In and Trench Warfare.
These doctrines are the essential, transformative ones. With their massive bonus to defense and entrenchment, they bring an end to the war of movement.
The four other doctrines are not necessary, but give some flavour to the war’s participants early-game. France and Austria are obvious adherants of the Cult of Offensive, while Germany begins with Auftragstatik already unlocked. Rapid Mobilization is Russia’s freebie, Guerilla Warfare is Serbia’s.
Most countries will move down this tree at the same speed, such that by mid 1914 they might begin to unlock Digging In. Germany, however, has an advantage in unlocking doctrines, while France has a major disadvantage that must be removed via focuses (a clever player will be able to do this early, and score that aforementioned reverse-Marne).
Without Pragmatic Uniform, France cannot move into the Digging In segment of the tree.
Digging In provides two enormous changes: +10 Organisation (a typical infantry division has 30 baseline organisation) means that a division attacking a division that lacks Digging In can out-tank it. +50% Defense makes it difficult for en enemy army lacking the doctrine to push back.
Meanwhile, the total +7 entrenchment from both doctrines increases entrenchment from a measly 2 (giving +10% attack and defense) to 9 (45%). This means if a division simply sits still for a while, it will get 45% stronger.
The upshot of this balance is that, given two even countries, one that has Digging In can overpower one that lacks it. When both attain Digging In, the front slows, and when they unlock Trench Warfare it tends to stop completely.
I’ve spent an enormous amount of time balancing this system, to say nothing of getting the AI to behave itself. To reach this point I’ve made heavy use of debug-tools, trial and error, my excel models, and best of all Sid Meier’s Double or Half balance method, to which I’m a complete convert after many years of making timid little tweaks.
The unit balancing model allows me to preview how unit stats will look based on input equipment stats. With it, I was able to figure out the right ratio of attack, defense, and breakthrough that would produce mobile war followed by trench war.
Some experiments with doctrine cost were needed to reverse-engineer how much Army XP is gained per day, as documentation was missing on the modding wiki.
Reconciling army sizes with issues like border density, historic figures, a manageable amount of divisions, and even just allowing Germany to steamroll Belgium, continues to be a headache. So I have a spreadsheet for that too.
I’m increasingly finding spreadsheets inadequate to predict the minutae of the game. However, the models are still useful to make a good guess before fine-tuning with playtests, on which I now spend a lot of time. A peek into my increasingly large playtest log:
After months of work on this problem, the results are a big achievement for me.
