The peace treaties that ended World War I have redrawn the borders of Europe not only in political but also in economic terms. With the dissolution of the Austro-Hungarian Monarchy, the shipping companies of Austria and Hungary not only flew the flags of separate sovereign states but also had to hand over a significant part of their fleet to the shipping companies of the newly formed states. This affected the first Danube Steamship Company particularly adversely since the Vienna-based Company’s Óbuda Shipyard had coal mines in the Pécs region on Hungarian territory just like the Mohács-Pécs Railway it also owned. The Hungarian River and Sea Shipping Company (MFTR) and the DDSG, together with their jointly owned Süddeutsche Dampfschiffahrts-Gesellschaft (SDDG) – in association with Bayerischer Lloyd (BL) – established a Danube cartel called the Operating Community (Betriebsgemeinschaft), in which they agreed on the prices and quotas for certain transports and services. Thus, the two companies applied preferential tariffs to each other in their own shipyards, putting their newly formed English, French, Yugoslav and Czechoslovak competition in disadvantage. The DDSG shipyard in Óbuda and the Company’s coal mining in the Pécs region played a key role in the Joint Venture.
However, the infrastructure of the new shipping companies with plants in Bratislava, Komárom, Belgrade and Orsova was not on par with the well-equipped shipyards in Budapest, Korneuburg or Linz. Czechoslovakia, for example, tried to improve this situation by investing significant resources in the development of the Bratislava port and the Komárom shipyard. Due to the Great Depression, however, both the DDSG and the MFTR went into administration and the state had to intervene. In the case of DDSG, due to the Italo-Austrian political rapprochement, new partial Italian ownership was established. The contracting companies began to slowly develop through the joint venture, which is well illustrated by the fact that in 1934, MFTR also launched the Budapest-Ruse express ferry service, catching up with the DDSG’s similar Lower Danube ferry service.
After World War I, shipping companies found it difficult to meet the exponentially increasing demand for oil transport on the Danube. The import of oil and oil products became particularly important for Hungary, so it was decided to build a petroleum port and oil refinery in Csepel. The key elements of oil transport in the Danube region were the Romanian pipelines leading to Constanța and Győr, where the oil was transferred to tankers and tank barges in the petroleum ports there. The transport of Romanian oil by sea was cheaper and more efficient than by the
Danube route, so Yugoslav oil imports went by sea. However, for Austria, Czechoslovakia, Hungary and partly Germany, the more expensive and complicated Danube waterway remained. Romanian oil not only served the needs of the hitherto predominantly coal-based industry but also the needs of the motorization that emerged in the era. This is indicated by the fact that new technologies based on petroleum products were already being applied in shipbuilding. Oil transportation therefore not only represented a market opportunity for investors but also had strategic importance.
During the CEEC era, oil almost completely replaced coal as fuel, and there was a need to replace the aging Danube fleet with modern vessels. From the late 1950s, shipping was transformed by taking advantage of motorization: steamboats with paddle wheels were slowly replaced by motorized pusher ships with screw drives.