Previous to the time when America became an important factor in air operations, during the late summer and autumn of 1918, superior power in the air had wavered back and forth between the opposing forces. American built planes and American fliers added to the Allied forces the air power necessary to insure supremacy. More and more important during the last year of the war had become bombing operations from the air and the United States had been asked to specialize for bombing and reconnoissance work in both plane production and training of personnel. American air work was therefore largely of this kind and its contribution to the final defeat of the enemy, both in the destruction of enemy troops and material and in the undermining of morale, was of very considerable importance. How important it was considered by our war associates is shown by the unstinted praise they gave to the ability, the skill and the daring of the American flying men. For their valor and achievements four hundred of those men received decorations. Over sixty of them were “aces”--that is, had received official credit for the bringing down of five enemy planes. The premier “ace” had twenty-six planes to his credit and the next highest had eighteen. Altogether, American fliers accounted for 491 enemy planes whose destruction or capture was confirmed by the very strict evidence required before official credit for them was given and 354 others were reported without this official confirmation. Of enemy balloons the destruction of eighty-two was reported, of which fifty-seven had official confirmation. The American forces lost forty-five balloons and 271 airplanes. Therefore the American Air Service at the front destroyed more than three times as many planes as it lost and almost twice as many balloons. Among the flying men there were 554 casualties, of whom 171 were killed in action. CHAPTER XX AMERICAN CONTRIBUTIONS As a part of the American effort for effective prosecution of the war in the air, American skill, ingenuity, knowledge and determination in research solved some problems in air navigation and air fighting that will be contributions as important to aeronautics in peace time as they were in war, when they helped to turn the tide of battle against the enemy. The account of American achievement in the delivery of telling strokes would hardly be complete without a summary of these developments, discoveries and new applications of facts or methods already known. Of great importance was the devising of the Liberty Motor, which met a keenly felt need for a high-powered engine for use in battle and observation planes and also made possible rapid production of motors in large quantities. Not only did this aid our war associates and hasten our own progress toward making our influence decisive at the front but it will have an important influence upon the commercial future of the airplane.