On 25 February 1942 Slovak pilots were sent to Karup, Denmark for conversion training to the Bf 109. The unit was then deployed to the Kuban area in the Crimea, on 27 October with 12 'Emils' on charge. It made its first aerial claim on 28 November 1942 when a pair of Bf-109s attacked nine Polikarpov I-153 biplanes, the Slovaks claiming three without loss. The Luftwaffe loaned several Bf 109 F-2s in January 1943, followed by Bf 109 Gs in March.
13 staffel flew some 2000 sorties and claimed around 216 kills for the loss of only four pilots killed (and three who defected to the Soviets). The leading ace was Ján Reznák with 32 confirmed victories and Izidor Kovárik with 28 confirmed victories.
On their return home, they were deployed in Western Slovakia for the industrial defense and of the capital of Bratislava, under the control of the Jagdfliegerführer Ostmark (Fighter Leader Austria). 15 Bf 109G-6 fighters were delivered in late January February 1944. The unit attacked the American heavy bomber formations on 26 June near Vienna. Eight Bf 109G-6s intercepted the bombers, and managed to shoot down a B-24, and damaging two others before five 109s were shot down by the escorts. Three pilots were killed, including the unit commander.