There are many reasons why it is useful to have an overview on railway history in Germany. Otherwise one would not really understand why e.g. most engines are electric, why some engines had different class designations and so on. The history of the railways is of course tightly interwoven with the political history of Germany, which has had several hard cuts in the 20th century.

I will concentrate on a short overview of the time that is playable in the set. Additional information can be found by starting with the Wikipedia article history of rail transport, from where you can dive deeper.

DBSetXL models most of the developments (major exception is the Reichsbahn era of East Germany) in the context of the game. Some of the focal points are therefore similar, such as early big electric engines as they were used in Bavaria or Silesia, or the well-known standard steam engines which were the backbone of transportation for decades. In the 1950 standardized electric engines come into play, as the German rail network is one of the biggest electrified networks in the world, which also causes Diesel engines to be underrepresented compared to e.g. the United States. Friends of modern rolling stock will be delighted at the ICE trains, which - as in real life - requires purpose-built tracks to reach highest speeds.

State Railways (-1920)

Until 1920 almost each state of the German Reich (Prussia, Bavaria, Saxony, ...) had their own state railway. So there were about a dozen state railways, each with their own administration, engine types and so on. This hampered operations and caused issues with maintenance due to many similar, but slightly different vehicles. For example, in Bavaria four-cylinder compound steamers were favored, such as the well-known S3/6 (later class 18), while Prussia concentrated on simpler construction and maintenance, as shown by the hugely successful P8 (later class 38).

Deutsche Reichsbahn (1920-45)

In the early 1920s the state railways the combined into the Deutsche Reichsbahn-Gesellschaft (German Federal Railways). The existing engine classes were renumbered into a standardized scheme. More importantly, new standardized types were being developed to replace the older rolling stock. With these types, maintenance simplification was a major factor, e.g. by being able to reuse parts such as wheels, cylinders, and so on, across classes. The introduction of new engines was a necessity, since after World War I many engines had to be handed over, causing a shortage of engines and rolling stock in general.

Technical developments were also visible in other areas. Electrification efforts, which had already been started before the war, were now increased. Starting in the 1930s, modern DMUs were running, such as the well-known "Fliegender Hamburger", an express train running between Berlin and Hamburg. In similar ways, modern exclusive trains such as the Rheingold-Express were operated.

One could now speculate where these developments could have gone, but with the outbreak of World War 2 in 1939 the railways became an integral part of war machinery, transporting soldiers and equipment. Railway lines and stations became important bombing targets, by the end of the war most railway infrastructure was more or less completely destroyed.

Another result of the war was the split of Germany into two states. In 1949 both the Federal Republic of Germany was founded, as was the German Democratic Republic. With these political developments, railway history also split up.

Deutsche Bundesbahn (1945-94)

During the 1950s the West-German Bundesbahn was focusing on phasing out steam engines. The class V200 diesel engine was introduced, as were the standardized electric engines of classes E10, E40, E41 and E50. Another modern train to shape the image of the Bundesbahn was the TEE.

In 1968 the numbering scheme was once again revised to allow for computer usage. For steam engines little changed, electric engines ended up in the range of 100 to 199, diesel engines got range 200 to 299. For example, the class E10 was renumbered to class 110, class E94 to class 294, class V200 to class 220 and so on.

As more and more families were able to own cars, branch lines became more and more unprofitable, many of them had to be closed during the 1960s and 1970s. In the meantime, replacing old steam engines was continuing. Technical milestones of the time were the introduction of class 103 for fast passenger transport with up to 200 kph, as well as the introduction of the diesel engines of class 218 (which was a whole family of similar looking engines), to replace steamers on non-electrified lines. By the end of the 1970s, all steam engines had been retired.

During the 1980s, developments concentrated on the preparation of high-speed transportation, requiring newly-built lines and a completely new rolling stock, the so-called ICE train. However, when that one was finally put into service, the political landscape had changed drastically...

Deutsche Reichsbahn (1945-94)

The Reichsbahn of East Germany was hampered by the results of the reparations after the war throughout their 40 years of existence. Modernizations or investing into electric engines were next to impossible, instead, focus was put into completely reconstructing steam engines to work with brown coal, as hard coal was not available domestically (historically the coal in use with the railways had either come from the Ruhrgebiet and from Silesia, both of which were now in foreign countries).

During the 1960s cheap crude oil became available via pipeline from the Soviet Union. Therefore the decision was made to concentrate on Diesel engines in favor of electrification (which would have required lots of expensive copper). These diesel engines were to be delivered from the Soviet Union on account of central planning throughout the Eastern Block. This resulted in, among other types, the class 132.

Electrification efforts were re-started by the late 1970s and especially after the oil-crisis of 1981, when the Soviet Union started to demand higher prices for their crude oil. During the 1970s the heavy freight engines of class 250 had been developed, in the early 1980s the universally usable class 243 was added. Nobody would have thought that these two classes would end up running in West Germany in about ten years...

Deutsche Bahn (1994-)

In 1990 Germany was reunited, which also meant a reunification of the railway administration. This had lots of manifold consequences: Many lines especially in East Germany were closed, a lot of engines was subsequently put of out service as well. Only a handful of classes could establish themselves in all of Germany (among them class 232 (ex 132), 155 (ex 250) and 143 (ex 243), replacing older West German classes.

The modern image of the German railways is represented by electric engines such as class 101 for fast passenger services, freight transportation is handled by several electric classes that can operate across European borders. Local traffic is mainly handled by EMUs and DMUs such as class 425 and 612, which are run by different operators, as the Deutsche Bahn is not the only operator on the network anymore. Another important change was the rollout of double-deck coaches for local trains (which is basically old news for East Germans, as these had been in use there for decades).

Bundesbahnzeit
The pages maintained by Ullrich Budde focus on a detailed view on the West German Bundesbahn between 1968 and 1990 and provide loads of photos of the everyday operations of that era. The sites are in German, but the focus is on photographs and photo galleries.

dbtrains.com
This site concentrates on the various German long-distance passengers trains, starting in the 1920s with the Rheingold, covering the TEE trains of the 1960s and 70s, up to the modern ICE trains. The page is in English.

Elektrische Bahnen
This page focuses on the development of electric transportation before 1945. It does not show much in terms of rolling stock, more concentrating on the necessary infrastructure such as power plants and power lines, and also discussing lots of the historical backgrounds. The whole page is in German.

Hochgeschwindigkeitszüge
The flagship of the modern German railways, the ICE in its different variants, is the focus of this page, as are the corresponding high-speed lines and high-speed railways in other countries. There are quite a bit of photos to be found as well, which is probably the most interesting part, as the whole page is in German.

Verein Schlesische Gebirgsbahnen
The railway lines in Silesia were some of the first to be electrified in Germany in the 1920s, due to the importance of the mining operations there. These pages contain lots of information on the railway operations of the 1930s, including tons of very interesting historic photographs. The focus ends with the end of World War 2, which resulted in Silesia becoming part of Poland. The pages are in German.