Carpathian Ruthenia (Subcarpathian Rus'), the easternmost province of prewar Czechoslovakia, was occupied by the Red Army in late 1944. A Soviet-organized local assembly requested union with the Ukrainian SSR, and Czechoslovakia formally ceded the territory in a June 1945 treaty, ratified by the Czechoslovak parliament in 1946. The region, home to Rusyn, Ukrainian, Hungarian, and other populations, became Zakarpattia (Transcarpathian) Oblast of the Ukrainian SSR and remains part of independent Ukraine today.
The Soviet Union pressured restored Czechoslovakia to cede Carpathian Ruthenia (Subcarpathian Rus'), which was annexed and incorporated into the Ukrainian SSR as Zakarpattia Oblast.
The 1930 Czechoslovak census counted 725,357 inhabitants of Subcarpathian Rus', including large Rusyn, Hungarian and Jewish populations; by the time of the Soviet annexation in 1945 the territory held roughly 800,000, its Jewish community of about 100,000 having been deported and largely murdered in 1944. Thousands of Hungarian and German men were deported to Soviet labour camps in 1944-45.
The annexation itself — Czechoslovakia's cession of 12,777 km2 and about 450,000 inhabitants, formalised on 29 June 1945 and in force from 30 January 1946 — caused no mass killing, and roughly 120,000 people left the territory. Deaths did occur in the November 1944 round-up of Hungarian and German men for Soviet forced labour ('malenkij robot'), concentrated in the Szolyva/Svaliava transit camp; Soviet lists cited by the Roman Catholic Diocese of Mukachevo record more than 27,000 Transcarpathians held in POW and labour camps by summer 1945, and contemporary accounts describe heavy mortality from starvation, typhus and cold, but no reliable enumeration of the dead exists, so no range is given here.
The Roman Catholic Diocese of Mukachevo, drawing on Soviet lists, records more than 27,000 Transcarpathians held in POW and labour camps by the summer of 1945 after the November 1944 'malenkij robot' round-up, with heavy mortality at the Szolyva/Svaliava camp from starvation, epidemic and cold.
Ukraine