All classical military theorists point out that military strategy and national policy are intermingled. Clausewitz devotes a lengthy portion of his treatise to the ways in which military action should serve the needs of the state; indeed, his most famous quote concerns politics and war. Most of the combatants in World War I seem to have forgotten that policy drives strategy.
When the Elder Moltke was Chief of the German General Staff, German war-plans and policy neatly interlinked however, during Schleiffen’s tenure as Chief of the General Staff that link between policy and strategy was lost. The Great Memorandum of 1905 ignored political reality in favor of a purely military solution. It was taken as a matter of course that diplomatic methods would fail as soon as mobilization began. There was also disagreement among the German leadership about exactly what German national policy should be. There were two camps, one called for annexations to protect the Reich, and the other was willing to return to the status quo ante. These two camps never reconciled and German strategy and policy were disjointed throughout the war. In the absence of clear policy objectives it was impossible for the commanders to plan military operations to support them even if the commander had been inclined to do so, which is doubtful at best.
French policy was simple; they desired to defend their border against German aggression while simultaneously recovering the lost provinces of Alsace-Lorraine. The French Plan XVII was designed to support these goals. The French failure was in their inability to successfully execute the plan they had. While a failure, the initial French plan did generally support French national policy and goals, though not completely. The French were so engrossed with recovering lost territory they forgot that the enemy has a vote and failed to realistically plan for a German invasion. In the end the French plan, while it seemingly supported national policy, in reality failed to do so because they ignored the German threat in their zeal for Alsace-Lorraine. Eventually the French modified their plans and were able, in concert with their allies, to effectively coordinate military strategy with national policy.
It is difficult to say to whether the British even had a coherent national policy at the outbreak of hostilities. They seemed to stumble into war as a means of maintaining their national reputation. As the war continued, they did in fact develop an integrated national policy and military strategy. The British goal was always to knock Germany out of the war and they never ceased looking for opportunities to further their policy. This led to spectacular failures such as Gallipoli and Kut, but these were failures the British could afford.
The Russian high command had planned a military policy that dovetailed nicely with national policy. The Russians had planned their opening moves with the French and their attempt at invading East Prussia greatly affected the battles on the Western Front in the opening months of the war. It was only later in the war that Russian plans became unrealistic. The Russian problem was an inability to put their plans into action. A moribund army combined with internal troubles constantly robbed the Russians of their potential. These troubles and the Russian failure to either anticipate them or react well led to the dissolution of the Russian state.
Of all the combatants, the United States probably had the most juncture between military plans and national policy objectives. America was in the war for the sole reason of defeating Germany, whose policy of unrestricted submarine warfare is what drove America into the war. The only criticism that can be made of the Americans is their refusal to parcel units out as replacements instead insisting on the creation of a separate American army. This insistence was in the end partially justified by the undeniable striking power of the unified American formation.
The Allies had more success at coordinating their military strategies with policy goals than did the Central Powers. This can be seen not because of militarism but more a result of the high esteem in which the military was held in Germany. The German generals were better able to pursue their purely military objectives because the Kaiser deferred more to them and distrusted the Chancellor this led to a lack of civil control of the military. The Allied powers, by contrast had a higher degree of civilian control of the military and thus the government was better able to impose control on the military strategy and keep it more focused on national policy.