When it comes to international politics, World War I pretty much has it all. That’s a blessing in some ways—there’s lots to be puzzled by, to explain, and to learn from—but in others, it’s not so great: any one event looks overdetermined when you look closely enough, and it’s inferentially impossible to prize some explanations over others. That said, we spent some time today talking about why the war lasted as long as it did. We finish the “real time” part of the course in December 1914/2014, but there were/are 46 more months of war to go. Why, after Germany’s defeat at the Marne, the onset of trench warfare on the Western Front, and the stalemating of the East, did the war continue until 1918? After all, while Germany suspected it was beaten in December 1914, it pretty much knew that it was in December 1917…and yet the war dragged on.

There’s a lot to draw on here, and if you want some accessible treatments of war termination in general check out this and this (both of which figure prominently in today’s story). To summarize the discussion, though, we emphasized that wars often end when fighting solves the problem that stood in the way of a settlement in the first place. When wars are driven by commitment problems, for example, they tend to end when either (a) commitments are made credible by removing incentives or abilities to renege or (b) the source of incentives to renegotiate (like rising power) are eliminated. This, of course, tends to push states towards particularly extreme war aims, from dismembering states to “ending” them as great powers to replacing their governments. On the other hand, when wars begin with states disagreeing about how a total war would play out, they end once fighting produces sufficient agreement that both sides can agree to save the costs of further fighting. (This happens a lot; there’s a damned good reason the vast majority of wars end short of what we talk about colloquially as military “victory.”)

Our first step was to see if these stories helped us explain why the war lasted so long, and they got us pretty far. Germany, for its part, was fighting a preventive war against Russia and its French ally, the solution for which was ending their run as great powers. The British, likewise, were fighting to make Germany’s commitment not to dominate the Continent credible. Both, of course, drive war aims towards totality, because solving them requires the ability to dictate some pretty harsh terms—terms you can only successfully dictate when your opponent is well and truly prostrate. Defeating an army in the field, especially when prevailing technology and doctrine favor the defense, simply takes a long time, and that helps explain why the war was so long. Total-ish aims didn’t come out of nowhere (though plenty of scholarship acts like they do), and here they emerged from commitment problems. Nice. Okay. One factor in favor of a long war.

But what about information problems? Some work argues that information problems can’t be a compelling account of long wars (here, here), but—especially in the case of WWI—I’m not sure that’s so hard and fast. Consider what our belligerents were uncertain about: the ability to hold out, to wage an attritional conflict by sustaining a war effort that drew over and over from a limited pool of labor and manpower, to bring (and keep) the whole of the population into the war effort, to outlast the other on the way to a “peace of exhaustion.” As opposed to valuations of the prize, per-battle chances of winning, or per-battle costs of fighting, it seems that the only way to prove how long one can hold out is to…well, hold out. In that sense, uncertainty over which side could sustain mobilization likely kept the war long as well—fighting before full mobilization wouldn’t be revelatory (and those involved knew this), but after that (1916, roughly), verbal claims of one’s ability to outlast the other simply couldn’t be credible. Fighting on was the only way to demonstrate that one could fight on, and that likely lengthened the war as well.

However, one can argue that this only gets us so far. By late 1917, with American troops arriving en masse to negate whatever advantages Germany won from the Russian separate peace, the game was clearly up; even gambling to try to hold on to parts of Belgium was likely a dead letter. Why did Germany still fight on? One possible answer is that the German elite was “gambling for resurrection“; expecting a pretty grim personal fate if they settled short of victory, they opted to throw everything into a pair of desperate gambles (unrestricted submarine warfare, then Operation Michael) that bet everything on slim chances of victory. After all, if peace would be disastrous, while the worst possible outcome of fighting on was also a disaster—why not fight and hope for a slim chance of survival?

It’s possible, then, that the commitment problems that drove belligerents to seek military victory, as well as the informational obstacles to judging the relative chances of success in a war of attrition, could explain why the war was a long one. However, why it ended in 1918—and in the way that it did, with a precipitous bottom-up collapse of the will to resist on the front lines—might require an appreciation of the fates awaiting the German leadership (at this point, dominated by the Army) if they did what in 1917 an outside observer might expect of them: settling on Allied terms.