In his interludes of peace, as well as, indeed, during his many trying campaigns, Frederick devoted himself to the pursuit of literature. Stimulated by this devotion, as well as, doubtless, by a desire to add to the distinction of his Court and to his own character as a patron of letters, he induced the great French wit to take up his residence at the Castle at Potsdam. After the Treaty of Dresden, which closed the second great Silesian War and inaugurated a ten years' peace, the King added to his other residences his famous Garden Cottage, Sans-Souci. Here the literary monarch and the flattering courtier met and eulogised each other's productions. There is no doubt that Frederick here appears at his best. He was himself a voluminous writer, and it is much more pleasing to picture him in his retirement, writing history and poetry, however feeble, and receiving the plaudits of sycophants, than deluging the Continent with blood. Here, too, occasionally came Wilhelmina, renewing her acquaintance with the great _littérateur_, with whom she had much sympathy in common. Voltaire's charmed life at Berlin was not, however, destined to be of long duration. After about two years the King seemed to grow weary of his intellectual favourite, and found excuses for cooling in his devotion. The circumstances under which Voltaire finally left Berlin were such that he, along with his niece, Madame Denis, were arrested, Voltaire himself only regaining his liberty after the lapse of a fortnight and on the mediation of the Margravine. This mutual friend endeavoured in vain to heal the breach between them. Although her own friendship with Voltaire was maintained during her life, the friendly character of the intercourse between him and her brother was never resumed. But further troubles were in store for Frederick--troubles which were destined to try the nerves and break the heart of his devoted sister. When, in 1756, the war with Austria broke out again, the Margravine felt the keenest interest in it, and followed her brother's fortunes with aching heart. Intelligence of the brilliant successes which he gained and the terrible defeats sustained in his single-handed conflict with the four Powers who took up arms against him was forwarded by Frederick to his sister as opportunity offered, and fearful was the strain which her unchanging love was called upon to sustain during the last two years of her life. Here is a letter from the King to his sister, reporting progress:-- "_Leitmeritz, 13th July, 1757._