Whether all these castles were to prove only castles in the air depended now on Maria Theresa. Old Austrian statesmen might doubtfully shake their bewigged heads, but their youthful ruler never wavered. Not a finger’s breadth of Silesia would she surrender; at no price would she voluntarily part with any of her inheritance. She well knew what her duty required, and the birth of a son (afterward the great Emperor Joseph II) vindicated this noble woman’s firmness and masculine strength of purpose. Her heart was full of faith and courage, and the joy her maternity brought her was shared by the people, who showed a touching devotion to her. This was the foundation upon which she built her hopes; and it was strong enough to warrant confidence in Austria’s future, though the present looked dark enough. England made an effort to mediate between Maria Theresa and her adversary, but Frederick rejected any compromise and demanded the cession of Silesia, with the threat that if it were not yielded to him he would seize not only it, but four other duchies beside. He could always be depended on to keep his word, especially when he made emphatic statements, and Maria Theresa’s cause seemed lost before it really was so. But she stood firm as a rock, in spite of her increasing danger; in spite of the faintheartedness of her ministers; in spite of the plots of her enemies; in spite of Frederick II’s confidence. At any cost the war must be carried on; she must not allow herself to be humbled. The time for negotiation was past; action must take its place; words were useless, deeds must decide. Maria Theresa’s prospects were dubious. The French had crossed the Rhine with a large force and joined Bavaria. Passau was taken by surprise; Linz had fallen; even Vienna was threatened, and would have been obliged to surrender had the enemy pressed its advantage that far.