DEVELOPMENT OF THE BATTLE.--The "atmosphere" of battle is thus depicted in "The Science of War": "When two armies are face to face and one is superior in numbers to the other, the commander of the smaller army is confronted by two problems. If the superior army is not yet concentrated, or is so distributed that the different parts cannot readily support each other, it may be defeated in detail. If the superior army is already concentrated, its commander may be induced, by one means or another, to make detachments, and thus to be weak everywhere. The first problem is solved by rapidity of manoeuvre, surprise marches, secrecy, feints to bewilder the adversary in his concentration, and action on unexpected lines. The second, by skilful threatening of points for the defence of which the adversary will detach forces; by concealment of his dispositions; and by drawing the adversary into terrain where part only of his superior forces can be employed." "The power of striking 'like a bolt from the blue' is of the greatest value in war. Surprise was the foundation of almost all the great strategical combinations of the past, as it will be of those to come. The first thought and the last of the great general is to outwit his adversary and to strike where he is least expected. To what Federal soldier did it occur on the {30} morning of _Chancellorsville_ (May 2-8, 1863) that Lee, confronted by 90,000 Northerners, would detach Stonewall Jackson with more than half his own force of 43,000 to attack his adversary in the rear" ("The Science of War"). Surprise was the chief cause of success in the _First Battle of Cambrai_ (November 20, 1917) when General Sir Julian Byng launched the III. Army at dawn against the highly organised defensive position known as the "Hindenburg Line." The wire entanglements in front of this position were exceptionally deep, and had not been broken by gun-fire. Behind them the Germans were resting in apparent security and such information as they were able to obtain by raiding reconnaissances was not corroborated by the fierce and prolonged artillery bombardment which was at that time regarded as the inseparable prelude to an attack in force. The advance was preceded by battalions of Tanks, with Infantry in close support, and was followed by Cavalry, to round up fugitives and disorganise reinforcements. The artillery had previously been strengthened and was directed against the support and reserve lines, to prevent the Germans from massing for counter-attacks and to break up their formations. Aircraft carried out reconnaissance during the battle from a low altitude and harassed the defenders with fire action. An advance was made into the strongest part of the German defensive system on a twenty-mile front to a depth of five miles, and secured upwards of 11,000 prisoners, 150 guns, and considerable quantities of stores and materials, and although after-events neutralised the initial