From The Making of Eastern Europe: From Prehistory to Postcommunism, by Philip Longworth (Lume Books, 2020), Kindle pp. 99-101:
The consequences of the war were grievous. The loss of manpower in this overpopulated region was the least of them. A large proportion of the survivors were exhausted, ill-clothed and had forgotten the skills they had possessed before the war. They were also ill-fed. Losses of livestock were to take twenty years to make up. Partly as a result of the dearth of draught animals, cereal production everywhere except Bulgaria had diminished by between a quarter and a half by comparison with 1913. Even if this had not been the case, the earning potential for agricultural exports, which had been very considerable before the war, especially from Romania, Hungary and Ukraine, had fallen sharply, for, thanks to the war, the United States and Canada had become the world’s granary instead of Eastern Europe. And increased production in the West had caused world prices to slump. Czech industry, among the least affected, was producing 30 per cent less than before the war; in most of the other countries production was halved. The war had also dissipated savings, so funds available for investment were scarce. Inflation grew apace, ruining many members of the middle classes; so did interest rates. Business confidence was very low.
Matters were made worse by the Peace Settlement, which allowed other criteria to override the concern to draw frontiers that made economic sense. As a result towns lost their agricultural hinterlands; villagers found their access to mountain pastures, on which they traditionally grazed their cattle, suddenly blocked by frontier posts; the headquarters and branch offices of many a firm found that, overnight, they were in different countries where different laws and taxation systems applied. Railways lines were cut off from their former termini and cities from their railway stations. Romania’s newly-acquired port of Bazias had no communications to link it with the rest of the country. Hungary’s second city, Szeged, once a thriving regional emporium, became a sleepy frontier town. Grass was soon growing on the once busy docks of Trieste, now part of Italy, which had no need of another port.
The new frontiers cut across communication systems in a way that made nation-building the more difficult and expensive. Resurrected Poland found herself with parts of three different railway networks, each with different gauges and signalling systems; and, since they had been built with military purposes rather than international trade in mind, they did not usually meet up with one another. In Czechoslovakia all the main lines ran north-south, radiating from the old centres of Vienna and Budapest, whereas the new country’s axis lay east-west. Her predicament led to a bitter struggle with Poland for possession of Tesin (Polish Cieszyn), whose stretch of line was the only link between the head and the tail of Czechoslovakia, although Tesin’s population was predominately Polish and its mines a hotly disputed prize for both countries.
Such predicaments encouraged the continuation of a ‘war psychosis’. There was not only a desperate concern to protect one’s territory against one’s neighbours (and, if possible, to acquire more from them), but a willingness to wage economic warfare and, when opportunity offered, to loot. When, with the encouragement of the Powers who wanted to see Bela Kun’s Communist regime brought down, Romanian troops occupied Budapest in August 1919, they carried away as much of the telephone equipment and railway rolling stock as they could, even if they could put it to no use. Hungary retaliated later by cutting Romania’s telephone access to the West. When Romania was in dispute with Yugoslavia, she closed the locks controlling the flow of water from the Danube and so brought river traffic on the Yugoslav side to a halt. The Czechs refused to supply Hungary or Austria with coal, or to allow Polish coal to be shipped to them across her territory. The frontiers between Poland and Lithuania and between Yugoslavia and Bulgaria were repeatedly closed, and it was to take fifteen years to repair a two-mile gap in the telephone line between Belgrade and Sofia. The beggar-my-neighbour attitude was also reflected in fierce tariff wars.