It was now that, for the first time, he experienced the inconstancy of fortune. An Austrian army under Charles of Lorraine threatened his communications with Silesia. Saxony was all in arms behind him. He found it necessary to save himself by a retreat. He afterwards owned that his failure was the natural effect of his own blunders. No general, he said, had ever committed greater faults. It must be added that to the reverses of this campaign he always ascribed his subsequent successes. It was in the midst of difficulty and disgrace that he caught the first clear glimpse of the principles of the military art.
The memorable year 1745 followed. The war raged by sea and land, in Italy, in Germany, and in Flanders; and even England, after many years of profound internal quiet, saw, for the last time, hostile armies set in battle array against each other. This year is memorable in the life of Frederic as the date at which his novitiate in the art of war may be said to have terminated. There have been great captains whose precocious and self-taught military skill resembled intuition. Condé, Clive, and Napoleon are examples. But Frederic was not one of these brilliant portents. His proficiency in military science was simply the proficiency which a man of vigorous faculties makes in any science to which he applies his mind with earnestness and industry. It was at Hohenfriedberg that he first proved how much he had profited by his errors, and by their consequences. His victory on that day was chiefly due to his skilful dispositions, and convinced Europe that the prince who, a few years before, had stood aghast in the rout of Molwitz, had attained in the military art a mastery equalled by none of his contemporaries, or equalled by Saxe alone. The victory of Hohenfriedberg was speedily followed by that of Sorr.
In the meantime the arms of France had been victorious in the Low Countries. Frederic had no longer reason to fear that Maria Theresa would be able to give law to Europe, and he began to meditate a fourth breach of his engagements. The Court of Versailles was alarmed and mortified. A letter of earnest expostulation, in the handwriting of Louis, was sent to Berlin; but in vain. In the autumn of 1745, Frederic made peace with England, and, before the close of the year, with Austria also. The pretensions of Charles of Bavaria could present no obstacle to an accommodation. That unhappy prince was no more; and Francis of Lorraine, the husband of Maria Theresa, was raised, with the general assent of the Germanic body, to the Imperial throne.