Messerschmitt Bf.109E - Romanian users

In December 1939 Romania ordered a batch of 50 Bf.109E to Bayerische Flugzeugwerke. The first 11 ones arrived during the spring of 1940 and the remaining 39 a year later.
They were assigned to the newly formed Grupul 7 Vanatoare (7th Fighter Group) that had three squadrons and was considered as the elite unit of the Royal Romanian Air Force. In June 1941 there were 36 of them in active service.
Romanian Bf.109Es took part in Opertation Barbarossa since the very beginning, escorting bombers to strike against Soviet airfields. On 23rd June 1941, sixteen Bf.109Es engaged 25 Soviet aircraft and managed to shot down six of them with the first loss being on 5th July when Adj. Llie. Vatamanu was shot down to Soviet anti-air fire.
After 1941 the Air Force was re-organized due to the losses it has suffered and 15 second-hand ex-Luftwaffe Bf.109E-7 arrived from Germany in early 1942 and reinforced the lines of the Grupul 7.
Grupul 7 was sent again, with just 37 Bf.109E, to the frontlines, in the autumn 1942 to the Stalingrad area, where they were surrounded in November 1942 by the Soviet counter-offensive but they managed to escape at the cost of 5 aircraft plus three more being left behind to be captured by the Red Army. The remaining ones joined the Grupul 5 (5th Group) which was reorganized as a mixed fighter/bomber group that remained at the front until February 1943 when they returned to Romania.
During March 1943 the Bf.109E of the Grupul 5 (ex-Grupul 7) were replaced by the more modern Bf.109G and the Emils were assigned to training duties or to the Escadrila 52 (52nd Squadron). This squadron, that initially was equipped with Hawker Hurricanes Mk.I, flew various cover missions over the Black Sea, but in 1944 they had to join the rest of the Air Force to intercept USAAF's 15th Air Force bombers.
In late August 1944 Romania switched sides and the Bf.109E were taged as outdated and didn't see any more combat action during World War II. Just after the war, in 1946 all of them were withdrawn from active service.

Sources:
1. http://www.worldwar2.ro/arme/?article=397
2. https://en.wikipedia.org/wiki/Messerschmitt_Bf_109_operational_history#Combat_service_with_Romania
3. Salamander Books - The Complete Book of Fighters
4. Signal Squadron - Aircraft In action 44 - Messerschmitt Bf-109 in Action Pt.1