on the left : Mirage IVA bomber
on the right: Mirage IIIE lightweight fighter
on the middle: Mirage IVC heavy fighter
In 1958, Dassault studied two fighters : one was the single engine Mirage IIIC, other was the twin engine Mirage IVC. The AdA choose the Mirage III for economic reasons; the IVC become the Mirage IVA nuclear bomber.