Despite all efforts of the authorities, these letters and other anti-war literature continued to circulate secretly. In November, 1915, Liebknecht, Frau Luxemburg, Mehring and Frau Zetkin gave out a manifesto, which was published in Switzerland, in which they declared that their views regarding the war differed from those of the rest of the Socialists, but could not be expressed in Germany under martial law. The manifesto was so worded that prosecution thereon could hardly have been sustained. The Swiss newspapers circulated freely in Germany, and the manifesto was not without its effect. The Socialist party saw itself compelled on February 2, 1915, to expel Liebknecht from the party. This step, although doubtless unavoidable, proved to be the first move toward the eventual split in the party. There were already many Socialists who, although out of sympathy with the attitude of their party, had nevertheless hesitated to break with it. Many of these, including most of Liebknecht's personal followers, soon followed him voluntarily, and the allegiance of thousands of others to the old party was seriously weakened.
Outwardly, however, what was eventually to become a revolutionary movement made no headway during the spring and summer of 1915. The shortage of food, although making itself felt, had not yet brought general suffering. The German armies had won many brilliant victories and suffered no marked reverse. Mackensen's invasion of Galicia in May and June revived the spirits of the whole nation, in which, as among all other belligerent nations, a certain war-weariness had already begun to manifest itself.
The open break in the Socialist party first became apparent at the session of the Reichstag on December 21, 1915. The government had asked for a further war-credit of ten billion marks. Haase had a week earlier drawn up a manifesto against the war, but the newspapers had been forbidden to print it. At this Reichstag session he employed his parliamentary prerogatives to get this manifesto before the people in the form of a speech attacking the war as one of aggression, and announced that he would vote against the credit asked. Fourteen other members of his party voted with him. The German people's solid war-front had been broken.