first practical all-metal aircraft was produced by Hugo Junkers, who also used a cantilever wing structure with a metal covering. The first flight tests of the initial flight demonstrator of this technology, the Junkers J 1 monoplane, took place at the end of 1915 heralding the future of aircraft structural design. 1916: Verdun and the Somme Creating new units was easier than producing aircraft to equip them, and training pilots to man them. When the Battle of the Somme started in July 1916, most ordinary RFC squadrons were still equipped with planes that proved easy targets for the Fokker. New types such as the Sopwith 1½ Strutter had to be transferred from production intended for the RNAS. Even more seriously, replacement pilots were being sent to France with pitifully few flying hours. Nonetheless, air superiority and an "offensive" strategy facilitated the greatly increased involvement of the RFC in the battle itself, in what was known at the time as "trench strafing" – in modern terms, close support. For the rest of the war, this became a regular routine, with both attacking and defending infantry in a land battle being constantly liable to attack by machine guns and light bombs from the air. At this time, counter fire from the ground was far less effective than it became later, when the necessary techniques of deflection shooting had been mastered. The first step towards specialist fighter-only aviation units within the German military was the establishment of the so-called Kampfeinsitzer Kommando (single-seat battle unit, abbreviated as "KEK") formations by Inspektor-Major Friedrich Stempel in February 1916. These were based around Eindeckers and other new fighter designs emerging, like the Pfalz E-series monoplanes, that were being detached from their former Feldflieger Abteilung units during the winter of 1915–16 and brought together in pairs and quartets at particularly strategic locations, as "KEK" units were formed at Habsheim, Vaux, Avillers, Jametz, and Cunel, as well as other strategic locations along the Western Front to act as Luftwachtdienst (aerial guard force) units, consisting only of fighters. In a pioneering move in March 1916, German master aerial tactician Oswald Boelcke came up with the idea of having "forward observers" located close to the front lines to spot Allied aircraft approaching the front, to avoid wear and tear on the trio of Fokker Eindecker scout aircraft he had based with his own "KEK" unit based at Sivry-sur-Meuse, just north of