The Ju 52 was a transport aircraft, roughly equivalent to the Allies' DC-3 Dakota, that was also modified to carry out bombing raids. A total of 4,845 Ju 52 were produced before and during World War II, leading to widespread use delivering men and supplies in support of the German war effort. The Ju 52 had previously seen service in the Spanish Civil War, where it took part in the Condor Legion's destructive raids on Durango and Guernica in 1937 which illustrated to the world—for the first time—the destructive potential and horror of strategic bombing. Unfortunately for its pilots and military passengers, by the outbreak of World War II, the Ju 52 was a thoroughly obsolete military design and unlike many other famous Luftwaffe aircraft, the "Tante Ju" was cumbersome, slow, and therefore vulnerable to attack. This resulted in many losses, namely at Crete and Stalingrad.