Image kindly via Peter Taghon.

Jan Maes served with the 4/II/2 Aé equipped with Fiat CR.42 at the time of the German invasion of Belgium in May 1940.

In the early morning on 10 May the II^ème Group was ordered to evacuated from Nivelles to Landing Field No 22 at Brustem.
At 06:05 five Fiat CR.42s took off from Brustem to provide cover for the airfield. The second patrol (Sous-Lieutenant Jean Offenberg, 1^er Sergent Maes and 1^er Sergent Alexis Jottard) attacked Dornier Do 17s and a Bf 109. Offenberg claimed one destroyed Do 17, and fired on one other aircraft, which dived away. One of the aircraft he shot at was a Dornier Do 17 of II/KG77, which was damaged east of Waremme at 06.30 (there are some confusion regarding Offenberg's claims and some sources only credits him with a damaged Do 17). Maes damaged a Dornier Do 17 of II/KG77, near St Trond at 06.30. This claim is not confirmed.

Maes ended the war with one damaged enemy aircraft. This was claimed while flying biplanes.

Claims:

Kill no.	Date	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1940
	10/05/40	1	Do 17 (a)	Damaged	Fiat CR.42		near St Trond	4/II/2 Aé

Biplane victories: 1 damaged.
TOTAL: 1 damaged.
(a) Dornier Do 17 of II/KG77 damaged east of Waremme at 06.30. This claim is not confirmed.

Sources:
Désastre à Schaffen - Christian-Jacques Ehrengardt, 2000, Aéro Journal No. 12
Additional information kindly provided by Lars Larsson and Peter Taghon.