Daimler-Motoren-Gesellschaft's (Daimler) experience in the automotive business prior to World War 1 (1914-1918) gave the company an advantage when it turned its attention to helping out the Imperial German war effort. By request of the German government itself, the company formed an aeroplane-making division in the middle of 1915 to help meet wartime demand for fighters. This resulted in their first venture into the field - the Daimler "D.I" biplane fighter, known to the company as the "L6" (design attribution given to Karl Schopper).
The aircraft followed basic form and function of existing types namely due to expediency. An over-under biplane wing arrangement was used (single bay, equal span) that incorporated parallel struts and support cabling. The mainplanes were fitted well ahead of midships but aft of the nose. The nose section housed the engine through a rounded, streamlined design approach to promote aerodynamic efficiency. An open-air cockpit was used to give the pilot the best possible all-around visibility - though this was mainly hampered by the biplane wing arrangement, a common failing of many fighters of the period. The upper wing member was, however, held relatively low against the top of the fuselage, giving the pilot a better view out over the aircraft thanks to a cut-out section of trailing edge. The fuselage was rounded for its length and tapered towards the rear at which point a traditional three-planed tail arrangement was featured. For ground-running, a strutted twin-wheeled main landing gear held up most of the weight of the aircraft - a simple tailskid bringing up the rear.
The engine of choice became the all-new, in-house Daimler D.IIIb V8 water-cooled/liquid-cooled piston engine developing an impressive 185 horsepower while driving a two-bladed (fixed pitch) wooden propeller at the nose in tractor fashion.
Armament were twin 7.92mm LMG 08/15 series air-cooled, belt-fed machine guns synchronized to fire through the spinning propeller blades by way of "interrupter" gear.
Dimensions of the finalized form included a running length of 23.10 feet, a wingspan of 32.5 feet, and a height of 9 feet. Empty weight measured 1,655lb against an MTOW of 2,040lb.
Because of engine issues, the L6 struggled to see its first flight, managing to reach its flight testing phase only in November of 1917 and this lasted into March of the following year. During this time, imbalance (tail heaviness) was addressed by reworking the mainplane's interior cellule arrangement. Once the issue was ironed out, the aircraft could be moved on to government hands for type testing/certification (as part of the second "Idflieg" fighter competition of 1918) and this was recorded in July of 1918.
During this showing, the aircraft exhibited power loss at high altitudes, restricting its operating ceiling. Nevertheless, the potential - and need - was there and German authorities contracted for an initial batch of twenty of the fighters that same month. However, before serial production could really ramp up, the war ended with the Armistice of November 1918 - first-deliveries of these fighters did not occur until December and, even then, just six were ultimately completed before the Armistice itself.
As tested, the aircraft had a maximum speed of 114 miles-per-hour with an endurance window of about two hours. Time to 19,700 feet was around 30 minutes. These figures placed the new fighter on par with other late-war offerings - offering nothing new nor better and was of largely conventional design and performance.