In July of 1941 two wings were formed in Zagreb, the 4th Legionnaire Fighter Wing and the 5th Legionnaire Bomber Wing. The structure of the 4th Legionnaire Fighter Wing consisted of two fighter wings, the 10th and 11th which were soon transferred to Jagdfliegerschüle 4 in Fürth near Nürnberg, Germany. Reinforced with 11 Bf-109 E aircraft on September 28, 1941, the 10th wing under the command of Capt. Vladimir Ferencina is being transferred to the Eastern (Russian) Front. By their arrival to Poltava (Ukraine), they were assigned to 3. Staffel Jagdgeschwader 52. On October 10 they began combat duty and scored their first air victory by shooting down Soviet R-10 aircraft.

The previously mentioned Jagdgeschwader 52 is also well known for its finest pilot and later the youngest Lufwaffe's colonel Erich "Ace of all aces" Hartmann. By the end of the war he scored 352 victories flying Messerschmitt Bf-109 G/K series aircraft. He began his career as a pilot in October 1941 in Russia.

Compared with Russian I-15, I-16 and I-153 aircrafts, Croatian pilots were flying the far superior Messerschmitt Bf-109 E-3, E-4, E-7 series although, by the time being, old and obsolete versions of Messerschmitt Bf-109 aircraft. Some of these aircraft were used in the North African theatre and were rather worn out and in poor condition. At the same time other German units were given a new Messerschmitt Bf-109 F series. On December 12, 1941 while the squadron was being transferred to Taganrog airfield on Azov seashores, the 11th Wing was being assigned to them, but with no aircraft.

By mid January the 4th Fighter Group was disbanded and the new 10th Reinforced Wing is being formed up with the remaining available crew and 7 operational aircraft under the command of Maj. Mate Culinovic. On February 25, the command was taken over by Lt. Col. Franjo Džal and the unit is being re-designated Jagdgruppe Džal within which the 10th Reinforced Wing operated. By April 7, the wing scored 28 air victories, when it was transferred to Maruipol airfield to participate heavy and intensive fighting on Kerch peninsula. By the end of April, the wing was re-designated Fliegergruppe Džal in order to increase its growing independency. During the month of June the unit operates in Sevastopol airspace and over western Crimean shores mostly involved in bomber escort, reconnaissance and free hunt missions.

Zlatko Stipcic, in front of Bf 109 E aeroport in Mariupolu winter 1941/42

By July 21, the wing performed over 1.000 sorties scoring 50 air victories. Based on this statistic along with the poor condition of flyable aircraft, the HQ persisted in acquiring the new Messerschmitt series, and Lt. Col. Džal finally succeeded in getting them. In July 1942, Croats were given 7 brand new Messerschmitt Bf-109 G-2 aircraft. At the same time Fliegergruppe Džal is now a part of Luftflotte 4 and is being re-designated 15. Kroat. /Jagdgeschwader 52. By the end of September 1942 the unit is being engaged in combat over Kerch peninsula, Novorossyjsk, Tuapsa, Krimskaya and Gelendchuk and is scoring over 100 confirmed air victories. In October 1942, the wing was reinforced with new crew, and new pilots trained in FFS Überprüfungschule in Prenzlau and Fürth in Germany.

In December 1942, unit Džal is heading back to Croatia for vacation after months of intense fighting with over 3.300 sorties, 164 confirmed air victories and 6 losses. The most successful pilot was Cvitan Galic with 28 confirmed (and several unconfirmed) victories in 255 sorties. For this exceptional success he was promoted to lieutenant.

By mid February 1943, after 3 months of vacation, the wing was once again re-assigned to Eastern Front operating from Kerch IV airfield located on Crimean peninsula. The pilots were involved in combat over Krimskaya, Ivanovskaya, Novorossyjsk, Kabardink, Gelendchuk, and Yeysk and were facing more advanced and better Soviet aircraft. Very often they dueled Soviet Air Guards units flying American P-39 Aircobra and British made Spitfire aircraft. During the months April and May 1943, they performed over 349 sorties and scored 29 air victories. The most distinguished pilots were Lt. Cvitan Galic with 34 air victories and Lt. Mato Dukovac to become a second ace with 13 air victories scored between May 15 and June 6.

By the end of June 1943, the wing was transferred from the Eastern Front. After some staffing changes and reinforced with newly trained pilots from Germany, the wing now under command of Lt. Maj. Mato Dukovac was re-assigned to Russia. At Nikolaiev airfield they received 10 Messerschmitt Bf-109 G-2, G-4, G-5 and G-6 series aircrafts. Operating over Crimea in the short time period from October 30 to November 2, the wing scored another 20 air victories, Lt. Maj. Mato Dukovac with 40 and Lt. Cvitan Galic with 38 confirmed air victories standing in front. By the end of summer 1943, the wing was given new Messerschmitt Bf-109 "Gustav" G-10 and G-14 series and was simultaneously being trained at Labiau airfield in Lithuania. After a short time period, the unit was transferred to Eichwalbe, Germany.

Mato Dukovac (far right), his Bf G-6 (black '<1') end of 1943, Krim

Croatian pilots during their tour on Eastern Front have performed over 5.000 sorties, with several of them being awarded the "Ace" title for 10 or more confirmed air victories and with the unit's total number over 300 confirmed air victories. The Croatian Air Force adopted German air victory confirmation system, which was only applicable if there is an eyewitness or material evidence of enemy aircraft being shot down. In accordance with that, many of their victories were officially unconfirmed. However, there is one indicator contributing to their success. One German Fighter Regiment during its 12 months tour on Eastern Front had lost 80 pilots of which 60 never managed to shoot down a single enemy airplane. Total number of lost Croatian pilots was 16 and 7 of them flew over to Russian side and managed to survive the war.

For the purposes of Croatian Air Force in January 1945, 10 Messerschmitt Bf-109 were delivered – series G-6, G-10, G-14 and according to some information one "Kufurst" K-4. They were all used for air patrol and briefly in operations in Srijem and Eastern Croatia.

One of the last skirmishes was south of Zagreb with Capt. Bencetic and Lt. Jelak engaging a group of RAF "P-51 Mustangs" with "Gustavs".

15./ Jg 52 Aces

Last name	Given name	Victories	Comments
Avdic	Zdenko	10	Kroaten-Staffeln 15./JG52
Bartulovic	Bozidar	8	Kroaten-Staffeln 15./JG52
Bencetic	Ljudevit	15	Kroaten-Staffeln 15./JG52
Boskic	Safet	13	Kroaten-Staffeln 15./JG52
Culinovic	Mato	12	Kroaten-Staffeln 15./JG52; KIA 7/Oct/1943
Dukovac	Mato	44	Kroaten-Staffeln 15./JG52; defected 20/Sep/1944 ( defected Soviets with wingman Sgt. Spoljaric, though his nephew Dane Dukovac claims this is not true)
Dzal	Franjo	16	Kroaten-Staffeln 15./JG52
Ferencina	Vladimir	10	Kroaten-Staffeln 15./JG52
Galic	Cvitan	38	Kroaten-Staffeln 15./JG52; KIA 6/Apr/1944
Gazapi	Dragutin	7	Kroaten-Staffeln 15./JG52; KIA 27/Nov/1943
Helebrant	Josip	11	Kroaten-Staffeln 15./JG52; defected 20/Apr/1945
Kauzlaric	Tomislav	10	Kroaten-Staffeln 15./JG52
Kranjc	Josip	9	Kroaten-Staffeln 15./JG52; KIFA 21/Dec/1943
Kres	Vladimir	6	Kroaten-Staffeln 15./JG52
Lasta	Jure	8	Kroaten-Staffeln 15./JG52; KIA 28/Oct/1942
Martinasevic	Stjepan	11	Kroaten-Staffeln 15./JG52; KIFA 23/Dec/1943
Martinko	Eduard	12	Kroaten-Staffeln 15./JG52
Mikovic	Veca	12	Kroaten-Staffeln 15./JG52; KIA 20/Jul1942
Radic	Stjepan	5	Kroaten-Staffeln 15./JG52; KIA 29/Aug/1942
Starc	Albin	11	Kroaten-Staffeln 15./JG52; defected 14/May/1943
Stipcic	Zlatko	12	Kroaten-Staffeln 15./JG52