Though the Austrian crisis had taken him unaware, Hitler acted with energy and speed. Mussolini’s neutrality was assured, there was a ministerial crisis in France, and the British government had made it known for some time that it would not oppose the union of Austria with Germany. On March 11, 1938, two peremptory demands were made for the postponement of the plebiscite and for the resignation of Schuschnigg. Schuschnigg gave way, and German troops, accompanied by Hitler himself, entered Austria on March 12. A Nazi government in Austria, headed by Seyss-Inquart, was established; it collaborated with Hitler in proclaiming the Anschluss on March 13.

France and Great Britain protested against the methods used by Hitler but accepted the fait accompli. The United States followed the British and French policy of appeasement, and the Soviet Union demanded only that the West should stop further German aggression and that the Anschluss should be handled by the League of Nations. The government of Mexico was the only one that did not accept the Anschluss, and it lodged an ultimately futile protest with the secretary-general of the League of Nations. A questionable plebiscite on April 10, held throughout greater Germany, recorded a vote of more than 99 percent in favour of Hitler.

Austria was completely absorbed into Germany. Any official memory of Austrian existence was destroyed and suppressed. Austria was renamed Ostmark (Eastern March); Upper and Lower Austria became Upper and Lower Danube. Immediately after the invasion, the Nazis arrested many leaders of the anti-Nazi Austrian political parties and a great number of political opponents, particularly communists and socialists. Many Austrians, especially those of Jewish origin, were forced into exile.

The Viennese events during Kristallnacht—a short but devastating period of pogroms against Jewish people and property throughout Germany on November 9–10, 1938—proved that anti-Semitism was more virulent and violent in Austria than in most other German areas. A significant percentage of the Jews killed were in Vienna, where dozens of synagogues and hundreds of Jewish shops and apartments were destroyed and plundered. The degradation of the Austrian Jewish community—including the widespread threats against Jews’ lives, the destruction or “Aryanization” (forcible confiscation) of Jewish property, and the exiling of Austrian, mostly Viennese, Jews—became known as the Viennese model (Wiener Modell), on which the Nazis based their later expulsion of Jews from all of Germany and German-occupied countries.

By the time World War II began in 1939, more than 100,000 Jews—roughly half of all Austrian Jews—had left Austria. When the fighting ceased, more than 65,000 Austrian Jews had perished, many of them in extermination camps. Jews were not the only victims of Nazi persecution. Thousands of Roma (Gypsies) also were deported or murdered, and tens of thousands of Austrians with mental or physical disabilities were killed, most of them at Hartheim Castle, a so-called euthanasia centre near Linz.

Austrians were overrepresented not only in the system of terror against Jews but also on the battlefields. During the course of the war, hundreds of thousands of Austrians fought as German soldiers; a substantial number of Austrians served in the SS, the elite military corps of the Nazi Party. By the end of the war, approximately 250,000 Austrians had been killed or were missing in action. An even greater number of Austrians were held as prisoners of war, many of them for years in camps in the Soviet Union. In addition, more than 20,000 Austrians were killed in U.S. and British bombing raids.

As increasing numbers of Austrian men were enlisted in the German army, the resultant lack of workers, together with the tremendous buildup of the armament industries, brought compulsory labour on a massive scale to Austria. Foreign workers from many European countries were forced to work in industry as well as agriculture during the war, as were many thousands of concentration-camp inmates, most of them from the Mauthausen concentration camp, near Linz, or one of its satellite camps. (About half of the approximately 200,000 prisoners in these camps—many of them Russian soldiers—died.)

While the great majority of Austrians were not Nazis, popular support for Germany’s wartime policies remained strong until the later phases of the war. The Austrian resistance was small, though it was by no means negligible. Left-wing resistance groups (mostly communists, with a smaller number of socialists) dominated, but conservative resisters (mainly Christian Socialists and monarchists) were active as well. During the war, tens of thousands of Austrians were arrested for political reasons; many of them died in concentration camps or prisons, and about 2,700 were executed. Additionally, a number of Austrians fought as Allied soldiers against the German army.

The resistance movement was hampered by the political antagonism that had weakened the First Republic of Austria between the two World Wars. This political divide was so deep and bitter that it blocked cooperation between Austrian émigrés and between the various resistance groups that had formed inside the country. Nevertheless, the possibility of reestablishing an independent Austria after the war was far from dead.

After the outbreak of the war, the Allied governments began to reconsider their attitude toward the Anschluss. In December 1941 Soviet premier Joseph Stalin informed the British that the U.S.S.R. would regard the restoration of an independent Austrian republic as an essential part of the postwar order in central Europe. In October 1943, at a meeting in Moscow of the foreign ministers of Great Britain, the U.S.S.R., and the United States, a declaration was published that declared the Anschluss null and void and pledged the Allies to restore Austrian independence; it also reminded the Austrians that they had to make an effort to rid themselves of the German yoke. Though the British prime minister, Winston Churchill, continued to make proposals for setting up a central European federation comprising the former Habsburg lands and even southern Germany, the European Advisory Commission in London assumed that Austria would return to sovereignty within the borders of 1937.

When Soviet troops liberated Vienna on April 13, 1945, representatives from the resistance movement and the former political parties were allowed to organize and to set up a free provisional government. Though Austria was once again an independent republic, the future looked more than bleak. Much of the infrastructure of Austrian cities had been damaged or destroyed, and the country emerged from the war as one of the poorest in Europe.