The United States destroyer _Cassin_ had an encounter with a German submarine on October 16, 1917. Though struck by a torpedo, she was not seriously damaged and made port safely, after having first attempted, until night broke, to discover her attacker, without succeeding, however. The patrol boat _Alcedo_, formerly a steam yacht, belonging to G. W. C. Drexel of Philadelphia, was torpedoed and sunk on November 5, 1917. She was the first fighting unit of the United States Navy to be lost since the war begun. Two weeks later, on November 19, 1917, the United States destroyer _Chancey_ was sunk as a result of a collision, twenty-one lives being lost. On December 6, 1917, the United States destroyer _Jacob Jones_ was sunk by a U-boat and 60 lives were lost. CHAPTER XXXV THE WAR IN THE AIR Aeroplanes, dirigible and other balloons are no longer considered freaks and curiosities, as they were at the beginning of the war. Their use has become an integral part of all military and most naval operations. On all fronts they are employed regularly and extensively, just as any other branch of the military and naval services. In considering, therefore, aerial operations at the various fronts during the six months' period--August 1, 1917, to February 1, 1918--in this chapter we shall treat only of such undertakings in the air which were carried out independent of the general military operations. Those events in the air which formed part of offensive or defensive actions have been mentioned in their proper place as part of the general narrative. In this direction it must suffice to state here that all forms of aerial activities were continuously carried on by all belligerents at all fronts to even a greater extent than before. Statistics as to losses of aeroplanes and of members of the various flying services are very incomplete and more or less unreliable, primarily because each side has been trying to keep the other in the dark as to actual increases or decreases in the effectives of their air service. Such figures as are available, however, will be given a little farther on. They must not be taken as final, even though it has been attempted to compile them with the utmost care. As in the past, air warfare, independent of military operations, consisted, of course, of German and Austrian attacks on French, English, and Italian territory behind the actual front, and of similar operations on the part of the French, English, Italian, and American air services against German and Austrian territory.