<p>The Château-Thierry campaign had brought out the need for some kind of night observation, and Mitchell authorized establishment of an experimental flight to test airplanes and techniques for the mission. The 9th drew the assignment and began a series of test flights to learn about the problem. Landings and take-offs were guided by small arc lights, placed on the field to outline the runway. Beacon towers were placed on the home aerodrome and in the battle zone, flashing a light signal in the International Code. Map coordination with the tower positions marked gave them approximate check point data, and observations of the ground were made by the light from parachute flares.
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<p>The 9th scored first on a night mission on 14 September, at the end of the St-Mihiel offensive, with a flight from 8:06 pm to 9:50 pm. Two days later, a night-flying Breguet encountered German night-fighters for the first time, at no loss to either side.
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<p>There also were 21 balloon companies in the campaign, 15 of them American and six French. They lost 10 balloons.
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<p>The First Day Bombardment Group was the hardest hit during the St-Mihiel campaign. It had been organized just a few days before the offensive began, and was composed of the 96th Day Bombardment Squadron equipped with the Breguet 14B.2, and the 11th and 20th Squadrons, both flying the Liberty-engined de Havilland DH-4. On the very first day, four officers and eight aircraft were lost from the strength of the First. Four days later, the 96th was withdrawn from action, having lost 14 aircraft and 16 pilots and observers in the four days of the St-Mihiel battle. Two days later it was the turn of the 11th to leave. It had flown against Mars-la-Tour to bomb the German troops and supplies there, and only one DH-4 returned from the six dispatched.
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<p>The 96th was dogged by bad luck almost from the start. It began operations on 18 May in the relative peace and quiet of the Toul sector. Its Breguets had come from a previous assignment at a French training field, and were somewhat the worse for wear. Spares were impossible to procure, and the planes were finally made airworthy by clever mechanics who improvised parts from discarded French farm machinery, a good source of high-strength wood and some useful steel fittings.
