All of the seventy Americans at Villingen wished themselves anywhere outside the prison camp, and most of all back on the firing line, helping to win. So much did they wish this that a few more daring than the rest had twice attempted to escape together. Their attempts had ended in failure, but that had only led them to spend months in making still more elaborate plans to gain their freedom. Not all could leave the camp, they knew. Many did not care to risk it, while thirty of the seventy Americans were doctors and thought they ought to stay and do what they could for their weak and sickly fellow prisoners. But in the final plan, sixteen men were to try this break for liberty. One of the men was Lieutenant Harold Willis of Boston, an aviator in the famous Lafayette Escadrille. He had been captured after a battle in the air. Not even fourteen months in a German prison could kill the daring spirit of this young lieutenant. Instead, the cruel treatment of the prisoners, the daily contact with the stupid German guards, made him long once more to cut through the clouds and bring down another boche. Accordingly, he became a leader in carrying out the plans for escape. Lieutenant Edward V. Isaacs, of Cresco, Iowa, an officer in the United States Navy, was another leader. He was crossing the Atlantic in the big American transport, President Lincoln, when it was torpedoed by the submarine U-90, on May 31, 1918. He went down with the ship, but came to the surface again and crawled up on a raft where he stayed until one of the lifeboats came by and the men took him off. But the boat had gone but a short distance, when the guilty submarine pushed its nose up through the surface of the water near by. Its commander ordered the lifeboat to draw near and the helpless oarsmen had to obey. When asked the whereabouts of the captain of the vessel, the men in the lifeboat answered that, as far as any of them knew, he had gone down with the ship. Then the commander, probably noticing his uniform, singled out Lieutenant Isaacs, demanded that he come on board the submarine, and informed him that if he did not find the captain, he would take him instead to Germany. Two days later, the U-boat carrying this American officer was sighted by two American destroyers. Immediately the destroyers made for the submarine and tried to sink it. The U-boat quickly submerged and floated far below the surface while the destroyers circled about for several hours dropping many depth bombs, five of which exploded not three hundred yards from the submarine. So great was the shock of these explosions that, in telling of his experiences afterward, Isaacs said it seemed as if the ocean shook the boat much as a dog shakes a rat.