To say that Ukraine could only exist as a German protectorate might seem to claim that the new Ukrainian state was illegitimate. I do not mean that. Given time a Ukrainian state could have used its control over the educational system to inculcate a sense of Ukrainian identity into most of its people. Independent Ukraine was certainly a more real country than, for example, the Iraqi state that Britain carved out of the carcass of the Ottoman Empire, in part to guarantee its access to oil. A basic problem for many post-imperial states is that empires by definition are made up of many peoples entwined by history and geography. Unravelling them is a tricky and often brutal business. No polity is worse equipped to do this than one that combines a Westphalian insistence on absolute sovereignty with European nationalism's obsession with language, history and blood. So an independent Ukrainian state would have been weak and conflict-ridden in its early decades but, granted German protection, by no means unviable.
The big question was whether a German-Ukrainian alliance, and more broadly a German order in east-central Europe, could have endured. In general terms one has to remember that creating the military basis for empire or even hegemony is only the first stage, and usually the easier one. For empire to last, a second and often more challenging stage of political consolidation is required and this entails the creation of both institutions and of legitimacy. Napoleon learned this to his cost. So did the British when they conquered an empire in North America in 1763 only to lose most of it within twenty years. Even after winning the First World War the British faced problems in consolidating their existing empire. In Egypt and India they succeeded, albeit at the cost of concessions. In Ireland they mostly failed. Though the post-war settlement allowed the de facto incorporation of much of the Middle East into the British Empire, here too there were great difficulties: in Iraq, London was forced to retreat towards indirect rule in the face of local revolt and limited financial resources. Attempts to control Constantinople and the Caucasus proved to be examples of imperial over-stretch and British forces had to be withdrawn.
So the question is, could Germany successfully have met the challenge of the second stage of empire-building in eastern Europe, namely political consolidation? If one looks at the German record of empire-building in 1917-18 then it is hard to be optimistic. This does not mean that German rulers were necessarily stupid or inhumane. The chief civilian administrator in Ukraine, for example, was a decent and intelligent man who tried to apply in Ukraine the lessons he had learned before the war from studying British land reform in Ireland and from his own experience in managing Japanese railways in Korea. This places the German effort in eastern Europe in its proper imperial context. But on the whole, German administration alienated local populations by its rigidity and authoritarianism, and clashes between the Germans and local nationalists were frequent. Only on the outer edges of their empire in Finland and Georgia was German intervention often both successful and popular. In Finland they were a shield for the Finnish elites and middle classes against the Russian Bolshevik neighbour and its native allies. In Georgia, a similar equation applied, but the Germans were also a welcome shield against the advance of their allies, the Turks, into the Trans-Caucasus.
But one has to remember the context in which the Germans were working. It takes some time to establish a stable basis for empire. In Iraq, for example, in 1918-22 the British had to crush a major revolt and re-think their whole political strategy before a stable imperial order acceptable both to themselves and local elites could be created. In 1917-18 Germany in eastern Europe was working under extreme pressure. All other considerations had to be subordinated to winning the war and this war must be won quickly before the German civilian population began to starve and before American reinforcements handed victory to the Allies. To a great extent German rule in the east boiled down to a vast and not very successful foraging expedition. Take out American intervention and add a peace born of stalemate on the western front and the situation would have been very different. At that point a German empire in the east would have been able to deploy not just military but also economic and cultural power to buttress its rule. In much of the region Germany was a natural economic partner and cultural model. On the other hand, reconciling some key German interests to policies essential to garner support in east-central Europe would sometimes have been very hard: as always the German agrarian lobby would have been among the most vocal and obstructive of these lobbies.
Success would have depended on the intelligence or otherwise with which the Germans went about building their empire. Most of the German civilian statesmen and the great majority of the leaders of the centre and left-of-centre political parties realised that a successful empire in the east had to be 'informal', must take local nationalisms into account, and had to operate through deals with local elites. The military leadership was cruder and both it and some of its civilian allies had far-reaching annexationist schemes. It is very hard to predict the results of the interplay between political groupings within a victorious Germany and between the German leadership and the realities it encountered on the ground in east-central Europe. Once the immediate wartime crisis was over some of the steam ought to have been taken out of the military leadership. Nevertheless, where German strategic interests or German minorities clashed with the locals - as in Latvia, Estonia and Poland - a particularly hard line was likely to prevail in Berlin.
Would a German informal empire in eastern Europe have been acceptable to the local populations? Merely to ask the question is sufficient to inspire apoplexy in local nationalists and often with good reason. For the Poles a German-dominated eastern Europe would have been a huge setback for their national cause, not least if German hegemony rested partly on backing Ukrainians in the venomous Polish- Ukrainian dispute over ownership of eastern Galicia. For the Latvians and Estonians, anxious to throw off the rule of Baltic German elites, German victory would also have been insupportable. Given population losses among Latvians due to war and emigration, a determined policy of German colonisation might actually even have succeeded in turning this small country into a German-majority land. In most of the Austrian Empire, German victory would have strengthened Austrian- Germans' power and boosted their claims that the German language must have priority in administration and education. But so long as the Habsburg monarchy survived (which it would have done in the event of victory) it would never have allowed any extreme version of German nationalism to prevail within its borders because to do so would undermine the dynasty's raison d'etre. Moreover, for some of the peoples of eastern Europe, most notably the Jews, German informal empire could have had great attractions.