He was sent back to Berlin in the winter of 1915-16, with instructions to be on his good behaviour. Ignoring these instructions, immediately after his return to the university he began a course of lectures upon "War as an evolutionary Factor in human History." The lectures were promptly prohibited, and Nicolai was sent to Danzig, where he was strictly forbidden to speak or write on political topics. Nicolai took exception to this order, on the ground that he was a civilian. Thereupon an attempt was made to administer to him the oath of loyalty and obedience. He refused. Summoned before a court-martial, and warned of the consequences of refusal, he persisted. He was thereupon reduced to the ranks, and for two and a half years was engaged in futile clerical work as a private in the army medical corps. Nevertheless, he finished his book, and it went to press in Germany. The first two hundred pages had been set up when an information against it was lodged by the chief clerk of a great submarine dockyard, who said indignantly, "We earn our money arduously in the war, and this fellow is writing in favour of peace!" Nicolai was arrested and his manuscript was seized. After a lengthy trial, he was sentenced to five months' imprisonment. The newspapers were forbidden to mention his name. The "Danziger Zeitung" was suspended for having published an account of the trial. His troubles began afresh immediately he came out of prison. The commandant of Eilenburg wished to force Nicolai to accept combatant service. Nicolai refused, and was given twenty-four hours to think the matter over. He thought of Socrates, and of the Greek philosopher's obedience to his country's laws, bad though they were. But he thought also of Luther, who fled to the Wartburg to finish his work. And Nicolai left that night. Not even yet, however, did he quit Germany, for he wished to make a last appeal to the justice of his country. He wrote to the minister for war, relating the infractions of law to which he had been exposed, and asking for protection against the arbitrary proceedings of the military authorities. While awaiting an answer, he took refuge with friends, first in Munich, then in Grunewald near Berlin. But no answer was received. He had, therefore, to expatriate himself. We know how he crossed the frontier, "in an aeroplane, two miles above the earth amid clouds formed by bursting shrapnel."[89] At dawn after Saint John's night, he saw the distant gleam of the sea of freedom. He reached Copenhagen. For the last time he addressed himself to the German government, offering to return upon guarantees that his rights should be respected, and that he should be reinstated. After eight weeks, he was declared to be a deserter. A raid was made upon his house in Berlin, and upon the houses of some of his friends. His goods were sequestrated. A demand was made for his extradition, upon the charge of stealing an aeroplane.--Then it was that, resuming freedom of speech, Nicolai wrote