Messerschmitt Bf.109B/C German users

The Bf.109B was the first serialed produced variant of the Bf.109. It was powered by the Junkers Jumo 210D rated at 661hp (493Kw) engine which drove a two-bladed propeller and was armed with 7.92mm (0.312in) MG17 machine guns placed in a cowl on the nose. When produced, a variable-pitch propeller was introduced and retrofitted to older models, which were known, extraoficially as the Bf.109B-2. They were assigned to the main German Jagdgeschwaders (Fighter Wings) but they were withdrawn from service before the beginning of the World War II as they were outdated. A total of 341 Bf.109Bs were manufactured either by Messerschmitt or by Fieseler or Erla Maschinenwerke under license.
The Bf.109C was the least produced variant of the Bf.109. It was produced from spring 1938 and was powered by a 690hp (515Kw) Junkers Jumo 210G engine with direct fuel injection. It featured also a strengthened wing that carried two extra machine guns making it four 7.92mm MG17. Various sub-variants were produced and this way, the C-0 was the pre-production aircraft, the C-1 was the production version and the C-2 was an experimental version with an engine-mounted machine gun firing through the propeller hub. C-3 version was a proposed version with the MG17 of the wings replaced with 20mm MGFF cannons and the C-4 was another planned version that was going to feature a 20mm MGFF mounted on the nose, but it didn't materialize.
A total of only 58 Bf.109C were produced by Messerschmitt. They served with some of Luftwaffe's Fighter Wings, but most of them were withdrawn from active service before the beginning of the war. However, some of them were used as night fighters until January 1940.

Sources:
1. https://en.wikipedia.org/wiki/Messerschmitt_Bf_109_variants
2. https://en.wikipedia.org/wiki/Messerschmitt_Bf_109_operational_history#Combat_service_with_the_Luftwaffe
3. Salamander Books - The Complete Book of Fighters
4. Signal Squadron - Aircraft In action  44 - Messerschmitt Bf-109 in Action Pt.1