Fw. Wilhelm "Willi" Roth Bf109E-3/N "Weisse 3", WNr.779, of 4./JG 26, POSSIBLE LOCATION Douai 30 km south of Lille. Shot down by a Bloch MB152 on 3 June 1940. POW for a short time. Note the 100 octane triangle - quite rare on a Westfeldzug machine
The presence of the high-octane (100) triangle may indicate that 'Weisse 3' was in fact originally a Bf109 E-3 equipped with 20mm MG FF cannon) upgraded to the Bf109 E-4/N standard, albeit with the old style windscreen retained. See Jochen Prien's 'JV der deutschen LW', Part 4/I, Page 311, Photo No. 290 showing 'Weisse 4', W.Nr. 1190, of this same unit 4,/JG 26 which was referred to as a Bf109 E-4/N (with the same old-style windscreen retained) piloted by Uffz. Horst Perez who belly landed it at East Dean in England on 30 September 1940. JG 26 was evidently one of the few Geschwader to receive the E-4/N model (and possibly a complement of DB601N engines for retrofitting the existing Bf109 E-3 aircraft) but it was believed that this was some time in early September 1940 (Galland flew a Bf109 E-4/N for the first time on 7 September 1940).
However it now appears that the Bf109 E-3/N model indeed existed and that it was delivered to II./JG 26 at the time of the Battle of France. It is perhaps little odd for a Gruppe to employ two different types of fuel (i.e. 87 and 100) in a situation where they were obliged to frequently change their air bases in order to continue providing the aerial cover for the rapidly advancing German army.
"On the Generalluftzeugmeister meeting on 19 July 1940 it was noted that up to that date one Gruppe (Wing, each with 3 Staffeln, or Squadrons with 12 planes) of Bf 109 had re-equipped with DB 601N "
Thus it would appear that II./JG 26 had a number of DB 601N equipped Bf109 E-3s, perhaps many more than previously believed, during the attack in the West (Fall Gelb) and the BoF. This was consequently most likely the Gruppe referred to in the July document quoted above. Other units seem to have received these engines during the BoB, often denoted by the C3 or C-3 triangle fuel marking when seen on Bf109 E-4/N instead of the "100" marking with the mentioned Bf109 E-3/N of II./JG 26.