These two pieces will be the soul of the counter-battery, they will be upheld in their action by a special group of numerous heavy batteries which will make opposition on all german batteries opening fire on the two heavy guns. The plan was prepared, but to realise it, important and preliminary works had to be executed, which took five days after Captain Jaumotte’s reconnoitring. These works consisted thus: first of all, the building of firing emplacements for the heavy artillery; establishing many telephone connections, needed since the creation of the special group, connections which had to perform not only the centralisation of the command, but also a perfect understanding between the director of the firing, the batteries and the observation-posts and the cross registering section, as well as the creation of antennas to receive the messages of aerial observations. The railway battalion, pushed on after three days of splendid and extraordinary efforts, the works sufficiently far to render the point of Eggewaertscappelle capable of bearing the firing of the heavy guns. The group of telegraphists and telephonists accomplished at the same time, grand and important works of liaison, which altogether constituted the tool of the firing director. A firing program was elaborated, a program which led the action on Leugenboom and on the Tirpitz battery (see site n^o 4) at the same time. The firing on the Tirpitz was assured by two heavy guns of 305 in position on the point of Coxyde-Bains. The 13^{th} of May, the two heavy guns of 305 were brought to the place of firing which had been chosen—the switch-point of Eggewaertscappelle—and a nice clear day was waited to open action. That beautiful day was longed for right up to the 20^{th} of May 1917. The execution of the genuine program was preceded by an independant firing directed on the German observation-post installed in the belfry of Eessen, with a 240 (10 inch.) gun in position at the East of Burg Molen, upheld by the special group. The tower was partially demolished. About 11 o’clock, the heavy guns of 305 of Eggewaertscappelle fired their first shot on Leugenboom, while the gun of Burg Molen continued its demolishing and blinding work on the enemy’s observation-post. A little while after the guns of Coxyde-Bains entered in action in their turn against Tirpitz battery. The observation of these firings were both terrestrial and aerial. The firing program was continued the following days when the weather was favourable for observation. On the 25^{th} of May, an aerial photograph of Leugenboom position was taken. It did not disclose the least damage to the concrete block, but its clearness sufficiently noted the gun carriage not yet armed, in the centre of the honeycomb which formed the platform.