The day of the horse was passing in the great war as far as his connection with the mobile artillery was concerned, and the gasoline motor was taking his place, this tendency being accelerated particularly by America, the greatest nation of all in automotivity. Trucks and tractors to pull the guns, motor ammunition trucks displacing the old horse-drawn caissons and limbers, even self-propelling platforms for the larger field guns, with track laying or caterpillar mounts supplying not only mobility for the gun but aiming facilities as well; these were the fresh developments. Some of these improvements were produced and put in the field, the others were under development at the signing of the armistice. The whole tendency toward motorization served to complicate ordnance production in this country, not only in the supply of the weapons and traction devices themselves, but in the production of increased supplies of ammunition, since these improvements also tended to increase the rapidity with which bullets and shell were consumed. The total cost of the ordnance alone required to equip the first 5,000,000 Americans called to arms was estimated to be between $12,000,000,000 and $13,000,000,000. This was equal to about half of all the money appropriated by Congresses of the United States from the first Continental Congress down to our declaration of war against Germany, out of which appropriations had been paid the cost of every war we ever had, including the Civil War, and the whole enormous expenses of the Government in every official activity of 140 years. To equip with ordnance an army of this size in the period projected meant the expenditure of money at a rate which would build a Panama Canal complete every 30 days. Above are sketched some of the difficulties of the situation. In our favor we had the greatest industrial organization in the world, engineering skill to rank with any, a race of people traditionally versatile in applying the forces of machinery to the needs of mankind, inventive genius which could match its accomplishments with those of the rest of the world added together, a capacity for organization that proved to be astonishingly effective in such an effort as the nation made in 1917 and 1918, enormous stores of raw materials, the country being more nearly self-sufficient in this respect than any other nation of the globe, magnificent facilities of inland transportation, a vast body of skilled mechanics, and a selective-service law designed to take for the Army men nonessential to the Nation's industrial efforts for war and to leave in the workshops the men whose skill could not be withdrawn without subtracting somewhat from the national store of industrial ability.