The Junkers team under Zindel built an efficient aircraft with double-wing flaps and outward-retracting main gears. The D-1 with diesel engines was put into service in the Luftwaffe to become the standard medium bomber.
 

Ju 86 first saw combat actions in Spain, as one of the weapons tested by the Luftwaffe in the Spanish Civil War. It fulfilled its role well, but the early versions were vulnerable even to biplane fighters.

Many D and E bombers fought in Poland, which was their last major operational theater. Later some converted Ju86s, served as high-altitude bombers and re-connaissance planes over Britain and Russia.