The class 50 was developed to be able to replace the heaviest freight locomotives with low axle loading from the various state railways. With the wheel arrangement 2-10-0, it has a considerable size, but due to the axle load of only about 15 tonnes, it could be used on almost all secondary lines. The most important class to be replaced was the Prussian G 10, which was present in very large numbers. Compared to this, only one leading axle was added in order to be able to increase performance despite the same axle load. 

The general design of the 50 was aimed at being able to manufacture larger numbers for a low price in many different factories. After the beginning of the war, the idea arose of the war locomotives or “Kriegslokomotiven”, which should be even simpler. To this end, individual assemblies were increasingly being replaced by simpler ones, for example by using disc wheels instead of spoked wheels on the leading axle or by using an easier-to-manufacture, angular sandbox. These machines were designated as transitional war locomotives or “Übergangs-Kriegslokomotiven” (ÜK) and formed the basis for the later Kriegslokomotive 52, which was very simply constructed from the start.

The problem with such a long locomotive on branch lines was often that there weren't enough turntables available or there weren't any at all, since mostly only tank locomotives were used there. For this reason, soon the tub-like tender developed for the 52 series was introduced, which also allowed reverse speeds of 80 km/h or 50 mph. 

After large parts of Europe were occupied by the National Socialists, the construction of the class 50 was introduced in many locomotive factories in the conquered countries. Even after the war, production continued until 1948, so that in the end 3,164 pieces were completed. After the war, a very large number of the 50 were still available in various countries, where they continued to be used for a long time. In Germany, the majority of 2,159 operational machines remained in the western zones and only 350 were still operational in the Soviet occupied zone. Other user countries were Poland, Czechoslovakia, Austria, Bulgaria and Denmark. In Romania, 282 replicas were made as the 150 series until 1959.

For a long time, the 50 remained the most important freight locomotive on routes with lower axle loads on the Bundesbahn. Some conversions were made, including some where the boilers of the class 52 were installed. These were made of an alloy that did not age as quickly, but the 52, with its greatly simplified assemblies, could not compete with the 50 in terms of power. A visually striking conversion was the replacement of the large Wagner smoke deflectors with smaller Witte-type smoke deflectors on almost all machines. In a large number of engines, the tender was equipped with a driver's cab. When computer numbers were introduced in 1970, the running numbers could only have three digits, and so the 50 became the series 050 to 053.

At the Reichsbahn in the east, freight train service was more concentrated on the larger numbers of class 52 units. Nevertheless, 208 units were later reconstructed as class 50³⁵, which will be described separately. With the 50⁴⁰, new locomotives were developed on the basis of the 50, which will also be the subject of a separate article. Finally, oil-fired conversions were designated as 50⁵⁰, of which 72 pieces were made. Since they were used more intensively due to their higher performance, they suffered from higher wear and were withdrawn in the early 1980s in perspective of the oil crisis. The last few examples of the class 50 were retired from the DR in 1987.

Due to the large number, many examples of the class 50 can still be found in various countries today, and a large number of them are still roadworthy. These are often used in front of special trains and some of them are used in this role all year round. Occasionally there are also events where the old freight train locomotives can be found in front of commercial freight trains , in accordance with their original purpose.