The Mirage IIIS C.70 is an upgraded version of the Mirage IIIC fighter jet, developed in Switzerland. At the time, Switzerland had a decent air force that included various subsonic fighter jets. However, the lack of a supersonic aircraft was a significant drawback. Therefore, the Air Force created a program to introduce a new fighter jet. Participants included the Saab 35, the G.91, the F-104, the Mirage IIIC, and the F-11F-1F. Ultimately, the Mirage IIIC was selected. In 1961, Switzerland purchased one Mirage IIIC aircraft. Subsequently, production was localized, and the aircraft was renamed the Mirage IIIS. The military planned to build 100 of these fighters, but the necessary funding was not allocated. Consequently, only 54 aircraft were built, 16 of which were Mirage IIIRS reconnaissance variants. The Mirage IIIS entered combat duty in 1967.

Work on improving the Mirage IIIS began in 1988. The most notable improvement was the addition of canards, which enhanced stability during takeoff and landing and increased maneuverability. The name of this modification, C.70, comes from "Canard Wing at 70%". The new fighter was also equipped with updated avionics. Most Mirage IIIS C.70s were decommissioned at the Mirage-99 ceremony in 1999. But a few remained in service until 2003.

The Swiss Mirage IIIS C.70 was introduced in Update 2.47 "Leviathans", as a part of the German aviation research tree. Compared to its French predecessor, the aircraft has updated avionics and can use SARH AIM-26 missiles. As for IR missiles, the aircraft has a licensed copy of the AIM-9E. The Mirage IIIS C.70 can also use the SEPR844 booster with its standard armament and new JATO rocket boosters. Disadvantages of the aircraft include high speed loss during maneuvers and the lack of any air-to-ground weapons.