Joll/Martel describes the mood before the war very well. He begins by stating the obvious fact that we cannot possibly know the mood because "we lack the detailed study of opinion in most countries."
There were many movements against war. They started with middle class organizations in favor of international arbitration. The support for such peace movements came from many things, one of which was the growing fear that "war was now becoming so costly and so deadly that it would in fact become impossible."
Two international peace conferences were held at The Hague in 1899 and 1907, but neither were taken very seriously. The first was a result of a proposal by Nic II. People mainly agreed as to not offend the tsar.
"We German pacifists have always recognized the right and obligation of national self-defense" (262).
The international socialist movement appeared confident that it could prevent war. The movement thought that the strength of the organized socialist parties would be sufficient to deter governments from making war. The socialists feared that money that funded the army would also fund movements against the workers themselves.
Kaiser Willy: "In the present social confusion it may come about that I order you to shoot down your own relatives, brothers or parents but even then you must follow my orders without a murmur" (265).
However much any socialists repeated their intention to carry out a general strike against war, they had made no actual preparations to do so. The German SDP was more realistic; they rejected the idea of a general strike against war. They were also committed to the idea of national self-defense.
The British "avereage men and women were delighted at the prospect of war" (272). Joll/Martel states that the mood before the war must be seem as the "product of a widespread revolt against the liberal values of peace and rational solutions of all problems that had been taken for granted by many people for much of the 19th century" (274).
In the last two decades of the nineteenth century a new type of strident nationalism had found its way into the writings of many Euroeans. This new nationalism was thought of as being a matter of instinct rather than of reason. There was a widespread belief that was was not only inevitable, but desireable. In every country children were taught to be proud of their characteristic national values. Programs like the Boy Scouts (and their equivalents in France, Russia, and Germany) assisted the state in these endevours.
When the decision for war came, governments were able to fight the war because their subjects accepted the necessity for it.