The year 1806 brought the French into Prussia. Marshal Ney visited Kalisch, and placed a score of cadets in the newly-formed Polish regiments. In due time the others, as they were given to understand, were to be similarly disposed of. Young Rahden wrote to his adopted father, begging to be removed from the college, lest he should be made to serve with the enemies of his country. But the old officer looked further forward than the impatient boy; he knew that it was no time for the youth of Prussia to abandon the military career; that the day would come when their country would claim their services. His reply was prompt, brief, and decided. "I will not take you home," he wrote; "for then you will learn nothing. Be a Polish or a French cadet, I care not; only become an honourable soldier, and all that is in my power will I do for you. But do not come to me like our young officers from Jena; for if you do, you will get neither bread nor water, but a full measure of disgrace. Your faithful father, T." This letter made a strong impression upon Von Rahden, and he nerved himself to endure what he now viewed as inevitable. For another year he remained at Kalisch, until, in December 1807, news came of the approach of Prince Ferdinand of Pless, who had thrown himself, with a few thousand men, between the French army, then on its march to Poland, and the Bavarians and Wurtembergers under Jerome Buonaparte. This intelligence caused universal alarm in the college of Kalisch, now become French. "On the broad road in front of our barracks, large bodies of Polish boors, in coarse linen frocks, were drilled for the service of Napoleon by officers in Prussian uniforms; certainly a singular mixture. At the cry--'The Prussians are coming!' they all ran away, the officers the very first, and this might have given me an inkling of the reasons and motives of my father's severe letter. Under cover of the general confusion, a Prussian artilleryman muffled me and six other Silesian cadets in the linen frocks of the recruits, and hurried us off through field and forest, over bog and sand, to the Prince of Pless, whom we fell in with after thirty-six hours' wanderings. We were all weary to death. Nevertheless, five of my companions were immediately placed amongst the troops, who continued their route without delay; only myself and a certain Von M----, still younger than me, were left behind, as wholly unable to proceed. Of what passed during the next six weeks, I have not the slightest recollection. I afterwards learned that I had been seized with a violent nervous fever, the result of fatigue and excitement, and that I was discovered by a Bavarian officer in a Jew tavern near Medzibor, close to the frontier. The uniform beneath my smock-frock, and a small pocket-book, told my name and profession, and under a flag of truce I was sent into Breslaw, then besieged, to my mother, whom I had not seen for seven years."