Northern Transylvania in the context of "Romania"

The Second Vienna Award was the second of two territorial disputes that were arbitrated by Nazi Germany and Fascist Italy. On 30 August 1940, they assigned the territory of Northern Transylvania, including all of Maramureș and part of Crișana, from the Kingdom of Romania to the Kingdom of Hungary.

The Kingdom of Romania, under the rule of King Carol II, initially maintained neutrality in World War II. However, fascist political forces, especially the Iron Guard, rose in popularity and power, urging an alliance with Nazi Germany and its allies. As the military fortunes of Romania's two main guarantors of territorial integrity—France and Britain—crumbled in the Battle of France, the government of Romania turned to Germany in hopes of a similar guarantee, unaware that Germany, in the supplementary protocol to the 1939 Molotov–Ribbentrop Pact, had already granted its permission to Soviet claims on Romanian territory.

In the summer of 1940, the USSR occupied Bessarabia and Northern Bukovina, severely weakening Romania and diminishing its international standing. Taking advantage of the situation, Hungary and Bulgaria both pressed territorial claims on Romania. The disputes, arbitrated by Germany and Italy, led to the further losses of Northern Transylvania and Southern Dobruja to Hungary and Bulgaria respectively. The popularity of the Romanian government plummeted, further reinforcing fascist and military factions, who eventually staged a coup in September 1940 that turned the country into a Legionary State under Mareșal Ion Antonescu in partnership with the Iron Guard. Romania officially joined the Axis powers on 23 November 1940. Antonescu assumed full control over Romania in January 1941 and invaded the Soviet Union with the Axis, providing equipment and oil to Germany and committing more troops to the Eastern Front than all other allies of Germany combined. Romanian forces played a large role during fighting in Ukraine, Bessarabia, and in the Battle of Stalingrad. Romanian troops were responsible for the persecution and massacre of 260,000 Jews in Romanian-controlled territories, though half of the Jews living in Romania survived the war. Romania controlled the third-largest Axis army in Europe and the fourth largest Axis army in the world.

The Holocaust saw the genocide of Jews in the Kingdom of Romania and in Romanian-controlled territories of the Soviet Union between 1940 and 1944. While historically part of The Holocaust, these actions were mostly independent from the similar acts committed by Nazi Germany, Romania being the only ally of the Third Reich that carried out a genocidal campaign without the intervention of Heinrich Himmler's SS. Various numbers have been advanced by researchers for the lives lost in the genocide, with most estimates in the range of 250,000 to 380,000. Another approximately 132,000 Jews from the Hungarian-controlled Northern Transylvania were killed during this period by the Nazis with the collaboration of the Hungarian authorities. Romania ranks first among Holocaust perpetrator countries other than Germany.