In 1938, the Reichsluftfahrtsministerium (German Air Ministry, RLM), issued a requirement for a new twin-engine heavy fighter to replace the Me 110. This type of combat aeroplane was known as Zerst rer (Destroyer). The first prototype flew in September 1939. The Me 210 proved very difficult to fly, having numerous deficiencies. It was said to be deadlier to its crews than the enemy. Nevertheless, the Luftwaffe ordered the Me 210 into production. Operational trials began in late 1941, but it was eventually acknowledged that the aircraft had to be redesigned in order to be accepted into Luftwaffe service. The whole Me 210 debacle proved a huge scandal. A redesigned variant, the Me 410 began to reach Luftwaffe units in mid-1943. Even if the Me 210 and Me 410 were similar in appearance, the latter had to be redesigned to avoid the extremely poor reputation of the Me 210. The Me 410 proved a quite successful aeroplane, being used as a heavy fighter and for reconnaissance duties. Its closest Allied equivalent was the British DH 98 Mosquito. More than 1,500 Me 210/410s were built in Germany and Hungary, with only two Me 410s surviving today.