At the time of the attack our battle-planes, by driving the enemy’s aircraft far beyond their lines, allowed our scout-planes to direct accurately the fire of our 75 mm. guns, and permitted the aircraft accompanying the assaulting waves of infantry to fly close to the ground and attack the enemy in their very trenches. To such a co-ordination of all our efforts is due the seizure, with a minimum loss to our troops, of most important positions. The Germans have a way of attempting to regain lost ground by counter-attacks in mass-formation, which has cost them terrible losses. Field artillery has a capital part to play in the repulse of these attacks, which are usually broken up by the rapidity and power of the barrages. The guns of 75 mm. are assisted by the groups of 105 and by the destruction groups of 155, and also by counter-battery or neutralization fire from the heavy artillery, according to the necessities of the moment. =4. Anti-aircraft artillery.= Airplanes are the most reliable and effective weapons against airplanes and Zeppelins, but it is impossible to command at all times a sufficient number of machines to prevent the enemy’s incursions. Behind the lines have been placed special sections of anti-aircraft guns of different sizes (75, 47, and 37 mm.) mounted on special carriages that allow vertical fire. Without entering into details, we may say that the fire of these guns has been rendered so accurate that, though every airplane thus attacked may not be destroyed, projectiles shower so close around them that they are forced to fly away at all speed. A certain number of aircraft are brought down by these guns every month. One of these sections hit and brought down a Zeppelin near Verdun in February, 1916; another shot down, near Compiègne, in the spring of 1917, a large Zeppelin on its way back from England. Quite recently five Zeppelins returning from a raid on London were brought down in France by airplanes and anti-aircraft cannon. We mention these well-known events as indicating the unquestionable superiority of the airplane over the dirigible, which, we repeat, has been of real military service only at sea. They also demonstrate that by increasing the number of anti-aircraft sections both behind the front and in proximity to the whole enemy line, the raids on open towns can be rendered impossible. The Germans have recently invented a new gun, probably a mortar, which projects with great accuracy and to a high altitude a big cluster of whirling balls of fire, each having a potential diameter of five or six feet of fire. The whole cluster has an apparent radius about as great as the spread of an airplane from tip to tip. These new projectiles, known as “flaming onions,” have been used principally on the British Front, and do not appear to have done much actual damage, but should a great number of them be discharged at large, slow-moving planes, they might become dangerous.