It was especially encouraging to the Allies that in this impressive victory only four French divisions participated, while it was known from prisoners taken that the Germans had five divisions in the field. The French owed much of their success to the daring work performed by their aviators. Dozens of airmen dashed here and there, taking observations, correcting artillery, and accompanying the infantry's advance. At intervals they dashed back to headquarters with detailed reports of what was going on, thus keeping the commander in chief in close touch with the operations of the troops. The German gunners seemed to have become unnerved by the rapidity of the French advance, and fired almost at random. They had no assistance from their own aviators, who were kept in subjection by the French airmen, of whom not one was lost during the day. The French did not overestimate the magnitude of the victory they had won. It compelled the Germans to move back their artillery, which up to that time was a source of danger to the French supply depots and works on the other side of the Meuse, and also laid open the flanks of the French position on Le Mort Homme. Owing to the swiftness of the advance and the disorganization of the German batteries the French losses were comparatively slight. As stated in the French official report the total number of prisoners taken on December 15, 1916, was 11,387, including 284 officers, and 115 cannon were captured, with 44 bomb throwers and 107 machine guns. This great victory was the last act of General Nivelle before assuming the chief command of the French armies on the western front. To this officer belongs the credit of drawing up the plan of attack, in which he was assisted by General Petain, at that time his superior officer. The assault proper was left to General Mangin. The four divisions engaged were commanded by such leaders as General de Maud'huy and General du Passage. During the night of December 17, 1916, German troops delivered a strong counterattack against the new French positions north of Douaumont. By hard fighting they succeeded in forcing the French out of the fortified position known as Chambrettes Farm, the farthest point which the French attained in their advance on December 15, 1916. The Germans were not allowed for long to enjoy their small success, for on December 18, 1916, the French returned in force and reoccupied the position which they now held intact. CHAPTER XV CANADIANS AT ARRAS--NIVELLE IN COMMAND In the afternoon of December 20, 1916, Canadian troops made an important raid on German trenches north of Arras on a front of 400 yards and succeeded in putting out of action, temporarily at least, an entire battalion of German infantry.