TANKS, engines of war first employed by the British in their attack on the Somme (France) in September 15, 1916. The application of the invention to war purposes is credited partly to Majoi General E. D. Swinton of the Royal En gineers and later of the British War Cabinet, who was the well-known "Eye witness" of the early part of the war, and to Sir William Tritton, who had it built and first used in action. But the propelling principle was the caterpillar farm tractor, invented about 1900 by Benjamin Holt of Stockton, Cal., which was used by the British army for tow ing huge guns over difficult fields. The development to a self-propelled fort heavy enough to withstand all but the heaviest calibred enemy fire and yet mo bile under unfavorable conditions was a simple one. As a motor-driven armored vehicle, carrying machine guns and similar pieces, it served principally both for purposes of defense and attack. The muddy ground, shell craters, trenches, trees, and barbed wire were traversed where an advance would have been im possible to infantry not so provided for. In essentials it acted as a sort of land battleship for the protection of attacking troops. The success of the tank was due in the first place to its internal com bustion engine, and in the second place to the traction device developed by Holt. The mechanism had tracks on the sides, composed of a series of steel shoes linked together, with joints shielded from dirt and mud, with idler pulleys for laying the shoes down in front and driving sprockets for picking them up in the rear. The uprights on the inner surface of the shoes formed continuous rail-like bands upon which the truck wheels rolled carrying the weight of the machine. The mode of locomotion in the tractor and the tank is the same, each lays down its own rails and rolls over them. The track belts run lengthwise clear around the body, the shape bringing the additional track surface into contact with the ground, and so distributing it that the pressure of a twelve-ton tractor per square inch is actually less than that of an ordinary man's shoe. The first ex perimental tank weighed about 40 tons. Its noise and cumbersomeness greatly hindered its effectiveness, but the idea proved to be sound and mechanical experts worked hard to improve it. As time went on and the improvements were effected the personnel so engaged began to be very numerous and a separate tank corps was formed under a general officer.
Later on in the war it was seen that the tank was to prove a decisive weapon. In the last phase of the war there was no other instrument that played a greater part in bringing victory to the side of the Allies. In 1916 a total of only 50 were shipped to France from the British shops. Before the end of the war the total number reached immense propor tions, and the improvements effected in them enabled General Foch to attack without preliminary bombardment in the summer of 1918, in the great counter offensive which proved the final turning point of the war.
The Germans on their side began to build tanks as a measure of defense, but the Allies in this one particular had got greatly ahead of them and the German tank never played any great part in the war. The secret had been well kept from the beginning and it was indeed from the fact that it was presumed to have no other purpose but to serve as a drinking water container for Mesopota mia that the machine received the name that stuck to it. As the weight and mo bility of the tanks were improved they began to give real service to the Allied ranks. The light tanks, which appeared in great numbers in 1918, proved the most effective of any. The French Ren ault tank was known as the "Baby Tank." The light British tank was known as the "Whippet." Each of these carried two men and a machine gun, one man directing the tank and the other operating the gun. These tanks were easy to operate. They could go at a rate of 12 miles an hour, could climb a hill well, cut barbed wire, and turn with ease in muddy and swampy ground. In weight they did not exceed 7 tons. Some of the other types of tanks went up to nearly 50 tons. Of this heavy type was the American tank, which aimed at uniting all the best characteris tics that had proved effective in the war and ended by being exceedingly cumber some. These big tanks carried two six pounder rapid-fire Hotchkiss guns and 4 Lewis machine guns. Some of them were armored with quarter-inch chrome steel and the engines were 105 horse-power of the Knight salient type. Some of the tanks were armed with a short-barrelled 75 mm. gun. The armor of most of the tanks was made strong enough to turn anything less powerful than a shell from a big gun, and when the Germans placed field guns in the first line this armor had to be increased in strength. What came to be called the "male" tank was distin guished from the "female" tank by its offensive weapons. The "male" tank was equipped with quick-firing guns ca pable of firing shells effective in putting machine guns out of action. The "fe male" tank carried machine guns only his favor he had behind him an admir able system of strategic railroads.
Rennenkampf himself, with a large army, was in the neighborhood, but his subordinate in command, Samsonov, with about 200,000 men was advancing through the lake region, defeating a Ger man force near Frankenau. Flushed by effective merely in meeting an infantry charge. All available wall space in the tanks was used for storing ammunition, and the vehicle was made as self-sustain ing as possible, although it was recog nized from the beginning that its most effective use was as a co-operative and auxiliary arm, to attacking infantry.