Not to be left behind by rivals Macchi and Fiat, Reggiane upped the ante with the Re.2001 Ariete (Ram), a very effective mid-war design based on its earlier Re.2000 fighter. Sporting a license-produced Daimler-Benz DB 601A and a redesigned wing structure, the Re.2001 was unfortunately never awarded production priority over its superior contemporary, the MC.202 Folgore although it was used to some extent as a night fighter and for homeland defense. Undaunted, Reggiane eventually mated the Re.2001 with an indigenous Piaggio radial engine and the result was the superb Re.2002 Ariete II, Italy's finest fighter-bomber of the war. It was so good that the Luftwaffe planned to develop a version with the Fw 190 engine but eventually settled with using all captured and newly produced units for its own, flying it primarily for ground attack missions against partisans in occupied France.

The first flight of the prototype Re.2001 was in July 1940, with planes first delivered for service in June of the following year. Variants included the Re.2001CB fighter-bomber and the Re.2001CN night fighter which was used extensively during the last year before the Italian surrender. The Re.2002, on the other hand, first flew just three months after its predecessor but did not enter squadron service until early 1942. It nevertheless saw widespread production and use after the surrender, mostly by the Luftwaffe.