In this page we have glimpses of the German anti-aircraft defences on the Baltic coast; these very guns may have blazed at the R.A.F. planes when they made their reconnaissance flights over this area. All the guns are controlled by a detector (Below), which gives the direction, height and speed of the approaching planes. In the second from bottom photo, guns of the anti-aircraft defence are coming into action and the equal jets of smoke from each show that they are firing a salvo with precision Aircraft Detector These 3.7 anti-aircraft guns could fire up to an angle of 70º and in this photograph taken when a German anti-aircraft gun on the Baltic was in action at night; we see it trained at its highest elevation against an enemy raider. In a few seconds more tracer bullets will be discharged into the dark sky. Tracer bullets made Blue lines against the sky, enabling other guns to be brought to bear. When many of these were in the sky the scene resembled a firework display.