This machine is one of the ten Bf 109 Ds that was delivered to neutral Switzerland another 80 Bf 109 Emils was delivered before the German invasion of France.

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 D-1, J-307 was one that joined the Swiss Air Force in the late 30-ties. By June 1945 it was to soldier on despite beeing outclassed by both German and Allied fighters.