The academy suffered from the seven years' war (1756-1763), but its regular work continued, though few new members were added during this period. From 1760 to 1764 no 'Memoires' were published. While Maupertuis was absent on account of the wars and in search of health, Euler acted as president, and proved himself well qualified for the duties of that office. But the king had no intention of filling it with a German. The man he wanted was d'Alembert, of Paris, to whom he offered a large salary, rooms in the palace and a seat at the royal table if he would come to Berlin. But d'Alembert belonged to the French Academy and did not care to leave Paris. Yet, through his correspondence with the king, in which during these years the best history of the academy is found, he directed the work of the German academy and determined its membership. Virtually he was its president, though the king as its protector may be said to have assumed that office himself. In these conditions the academy became more French in its spirit than ever. In spite of the fact that the forty-six years of Frederick's academy were years of the first importance for the development of science and literature in Germany, neither the king nor his French presidents took any notice of the new spirit which had arisen among the German people, and had begun to show itself in the academy. Euler, disappointed at the turn matters had taken, after twenty-five years of hard work in Berlin, asked leave to return to St. Petersburg. For a time the king declined to grant the request, but its renewal finally secured his assent, though without any recognition of the fame Euler 's attainments and publications had brought the academy and Berlin. Ten years later, on accepting honorary membership in the St. Petersburg Academy, at that time a rival of the Berlin Academy, the king wrote Euler a letter accepting the honor secured for him, and in it made something like an atonement for former neglect. La Grange, of Turin, second only to Euler as a mathematician, was elected to the vacancy Euler 's departure had made, and about the same time J. Heinrich Lambert, another mathematician of note, came into the academy. Prior to d'Alembert's connection with it the Eulers, father and son. Pott, Marggraff, Gleditsch, Merian, Sulzer and Suessmilch had given it fame. Other men of rare ability had been persuaded to come to Berlin with the promise of membership in it, but with the understanding that they were to teach in the Ritterakademie, an institution in which the king took much pride and which he founded.
Not many changes in the academy took place during the last sixteen years of Frederick's reign. Between 1766 and 1770 two volumes of 'Memoires,' which the war had prevented from appearing, were published. With the next issue a new series of 'Memoires' was begun, greatly improved in binding and paper. Each of these new volumes contained a brief history of the work of the year.
