The original design of the Me 210 was born in late1937 to overcome to some shortcomings of the Bf 110. In autumn 1938 RLM awarded a contract to Arado and Messerschmitt simultaneously for the development of a Bf110 replacement. The resulting Messerschmitt design consisted in a mere improvement of the basic design with more powerful powerplants and heavier armament. Large use of Bf 110 components was made also. On the other hand, Arado’s answer to the requirements was the Ar 240.
After the first flight test of the Me 210-V1 the plane had to be heavily modified for its flying capabilities were barely poor. It had problems with longitudinal and lateral stability, and these were not suitable for a firing platform such as a combat aircraft. The design was improved by deleting the original twin vertical surfaces, similar to those of Bf 110, and fitting a large traditional vertical stabilizer and rudder.
Even while flying test were still going on, the RLM placed an order of 1000 Me 210 As in mid-1940. The first pre-production planes were under trials in a new established special test unit Erprobungsgruppe 210 at the end of 1940. The ErG 210 was to conduct operational testing of the Me 210 and develop combat tactics for the fighter-bomber. This unit was already well known, during the battle of Britain in Summer 1940, while it mainly flyed the Bf 110s and 109s awaiting for Me 210 deliveries. Its first leader was Hauptmann Walter Rubensdörffer, killed in action in a Bf 110 over England before he could ever fly a Me 210. Another important victim was Oberleutnant Heinz Forgatsch of 3./SKG 210. He died in an accident while testing a Me 210 at Rechlin.
Production began in Spring 1941 in both Augsburg and Regensburg factories; first deliveries began in April 1941.
A very important innovation in the Me 210 design was the use of side rear firing Mg131 turret guns (barbettes) controlled by the rear crew member by the means of a ReVi gun sight and a pistol grip with the firing trigger. These barbettes were delicate maintenance pieces and were not easy to handle. A famous victim of these guns was the American Ace Captain James Morris of the 20th Group. On 7/07/44, over Halle and Bernburg, he was shot down and killed in his P-38 Lightning by an attacked Me 410.
By the end of `41 the test program was over and the final evaluation was that it was still an unsuitable firing platform for its stability problems. Messerschmitt modified a pre-production plane (Me 210 A-0 NE+BH Werk Nr. 101) with lengthened rear fuselage (lengthened by 1½ panels) and redesignating it with the Versuch-number V17 on 14/03/42. This modification was very successful in increasing the plane’s handling qualities. Another important modification was the fitting, in July 1942, of wing leading edge slots. Soon after flying tests it was ordered to retrofit all Me 210 As with this device.
The Me 410, was an improvement of the Me 210 proposed as a high altitude fighter/bomber with two DB 603A engines (1750 hp), wing edge slats, a presurized cabine, lengthened engine nacelles and no sweep back on the wings. The Me 410 was waited everywhere in all fronts by 1943 and arrived too late. When it finally arrived, it was usually limited to the role of high-speed bomber or reconnaissance. The Hornisse was more successful in Observation units 1 and 7 than in the interceptor role.
The first prototype V1 was ready by the end of 1942. The entire test program envolved some twenty test planes many of which were modified Me 210s. The armament was the same as in the Me 210.
Projects wanted the Me 410 night fighter version, designated Me 410-D, to be equipped with Lichtenstein C-1 or SN-2 air intercept radar system, flame extinguishers for the exhaust pipes, and armed with four MK 108 30 mm high-speed cannons and two Mg 151 20 mm cannons as bow armament as well as two MK 108 used as schräge Musik angled cannons. The outer wing surfaces were to be built in wood to conserve strategic materials. Unfortunately this configuration never saw service nor either transformed in factory according to records.