During the night of 17/28 April 1944 the Night fighter Experten Oblt. Johnen shot down two Lancasters, but soon created an international crises of technological warfare.

While attacking a third Lancaster close to the Swiss border, Johnen's port engine was hit by return fire and had to be switched off. In trying to return to base he became completely dis-oriented when coned by several searchlights, causing him to land his aircraft at the nearest illuminated airfield. This turned out to be Dübendorf in neutral Switzerland.

Equipped with the highly secret Fug 220 SN-2 and FuG 202 AI radars, FuG 350 Z Naxos passive radar homing device, and the Schräge Musik weapons arrangement, this machine would be a valuable war-prize for Allied intelligence. The Germans and Swiss however swiftly came to an arrangement. On the 19th of May this machine was blown-up by the German agent, Hptm. Hans Brandt, who disguised as an aircraft-salesman, had flown in on a regular Swiss-Air flight to Dübendorf.

As a part of the agreement German would supplied Switzerland with 12 newly manufactured Me 109 G-6s. These planes were a welcome addition to the Bf 109s that had been delivered to neutral Switzerland before the German invasion of France, no less than ten Bf 109 Ds and 80 Bf 109 Es had by that time been delivered.

These 109s steadfastly guarded Swiss airspace during the summer months of 1940. Starting with the Battle of France, Swiss fighters began intercepting and occasionally fighting German aircraft intruding Swiss airspace. On 10 May 1940, several Swiss Bf 109s engaged a German Do 17 near the border and in the ensuing exchange of fire, the Dornier was hit and eventually forced to land near Altenrhein.

On 1 June, the Flugwaffe dispatched 12 Bf 109 E-1s to engage 36 unescorted German He 111s of KG 53 that were crossing Swiss airspace to attack the Lyon-Marseilles railway system. The Swiss Air force sustained its first casualty in the engagement when Leutnant Rudolf Rickenbacher was killed when the fuel tank of his Bf 109 exploded after being hit by the Heinkel's return fire. However, the Swiss "Emils" shot down six He 111s.

On 8 June, a C-35 observation aircraft, an antiquated biplane, was attacked over the Jura Mountains by two German Bf 110s; the pilot and observer were killed. Later on the same day, the Swiss Hauptmann Lindecker led about 15 Swiss Emils to intercept a formation of German He 111s escorted by II./ZG 1's Bf 110s. The engagement resulted in five Bf 110s being shot down (including the Staffelkapitän Gerhard Kadow) for the loss of one Swiss Bf 109.

This final resulted in that the German goverment threatened the Swiss with an invasion, and no more interceptions of German planes were made. However interceptions of Allied aircraft, especially USAAF flown machines was made. resulted in a number of clashes that prompted the Swiss to paint their 109 with red and white striped "neutrality markings" around the fuselage and main wings to avoid confusion with German 109s.

This Messerschmitt Bf 109 G-6, J-711 Werk. Nr. 163815 from Fliegerkompanie 7, was one of the 12 109s that joined the Swiss Air Force in late May 1944. The aircraft originally had the Stkz: NF+FP. It would later been equipped with a "Galland hod" and and fitted with a wooden tall tail.

Finally by May 1948 all the delivered 109G-6s was withdrawn from service, after suffering from numerous manufacturing defects and a problematic time of service. The 109 Es on the another hand continued in service until December 1949.