The Messerschmitt Me 210 was a German heavy fighter and ground-attack aircraft of World War II. The Me 210 was designed to replace the Bf 110; design started before the opening of World War II. The first examples of the Me 210 were ready in 1939, but they proved to have unacceptably poor flight characteristics from serious design flaws. A large-scale operational testing program throughout 1941 and early 1942 did not cure the aircraft's problems.