Thanks to the victories against Austria by the French-Italian coalition (the Battle of Solferino, 1859) and Prussia (Battle of Königgrätz, 1866), Hungary would eventually, in 1867, manage to become an autonomous part of the Austro-Hungarian Empire (see Ausgleich). Having achieved this, the Hungarian government made an effort to nationally unify the kingdom by Magyarisation of the various other nationalities. This lasted until the end of World War I, when the Austro-Hungarian empire collapsed. On November 16, 1918, an independent Hungarian Republic was proclaimed. Following World War One, Romania occupied Transylvania and Eastern Hungary, Czechoslovakia Upper Hungary. The joint Serb and French army occupied Southern Hungary. The Entente backed the subsequent annexations of these territories. In March 1919 the communists took power, and in April, Béla Kun proclaimed the Hungarian Soviet Republic. This government, like its predecessor, proved to be short-lived, despite some initial military successes against the Czechoslovak army.----------On 13 June the Peace Conference in Versailles ordered the evacuation of the northern territories by Hungary together with the evacuation of the Tiszántúl by Romania. Hungary fulfilled the request on 30 June but the Romanian army remained in the Tiszántúl. The ensuing war between Hungary and Romania led to the defeat of the Hungarian Soviet army. By August more than half of present-day Hungary, including Budapest, was placed under Romanian occupation, which lasted until November. Rightist military forces, led by the former Austro-Hungarian Admiral Miklós Horthy, entered Budapest in the wake of the Romanian army's departure and filled the vacuum of state power. In January 1920, elections were held for a unicameral assembly, and Admiral Horthy was subsequently elected Regent, thereby formally restoring Hungary to a kingdom, although there were no more Kings of Hungary, despite attempts by the former Habsburg king to return to power. Horthy continued to rule with autocratic powers until 1944.------------On June 4, 1920 the Treaty of Trianon was signed, fixing Hungary's borders. Compared with the pre-war Kingdom, Hungary lost 71% of its territory, 66% of its population, and with the new borders about one-third of the Magyar population became minorities in the neighbouring countries. Hungary also lost its only sea port in Fiume (today Rijeka). Therefore, Hungarian politics and culture of the interwar period were saturated with irredentism (the restoration of historical "Greater Hungary"). Horthy made an alliance with Nazi Germany in the 1930s, in the hope of revising the territorial losses that had followed World War I. The alliance did lead to some territories being returned to Hungary in the two Vienna Awards. Hungary then assisted the German occupation of the Kingdom of Yugoslavia, occupying the Banat right afterwards, and finally entered World War II in 1941, fighting primarily against the Soviet Union. In October 1944, Hitler replaced Horthy with the Hungarian Nazi collaborator Ferenc Szálasi and his Arrow Cross Party in order to avert Hungary's defection to the Allied side, which was constantly threatened since the Allied invasion of Italy.----------------Hungary was the first modern nation to pass distinctly anti-Semitic laws; the "numerus clausus" laws of the early 1920 were aimed at restricting the access of Jews to higher education. In the late 1930s, more specifically anti-Semitic laws followed. Some massacres of Jews by Hungarian forces took place in the early part of the Second World War, but Hungary initially resisted large scale deportation of its Jewish population. Ultimately, however, during the German occupation, the Arrow Cross Party and government authorities participated in the Holocaust: in May and June 1944, Hungarian police deported nearly 440,000 Jews in more than 145 trains, mostly to Auschwitz . Ultimately, over 400,000 Jews in Hungary were killed during the Holocaust, as well as tens of thousands of Roma people. Hundreds of Hungarian people were also executed by the Arrow Cross Party for sheltering Jews, among them Sister Sara Salkahazi. Foreign heads of states and diplomates who helped save the lives of many include Pope Pius XII, Raoul Wallenberg, and Carl Lutz.-----------Following the fall of Nazi Germany, Hungary became part of the Soviet area of influence and was appropriated into a communist state following a short period of democracy in 1946-1947. After 1948, Communist leader Mátyás Rákosi established a Stalinist rule in the country, which was hardly bearable for the war-torn country. This led to the 1956 Hungarian Revolution and an announced withdrawal from the Warsaw Pact which were met with a massive military intervention by the Soviet Union. Nearly a quarter of a million people left the country during the brief time that the borders were open in 1956. From the 1960s on to the late 1980s Hungary was sometimes satirically called "the happiest barrack" within the Eastern bloc, under the rule of late controversial communist leader János Kádár, who exercised autocratic rule during this period. In the late 1980s, Hungary led the movement to dissolve the Warsaw Pact and shifted toward multiparty democracy and a market-oriented economy. On October 23, 1989, Mátyás Szurös declared the Third Hungarian Republic and became interim President of the Republic. The first Free elections were held in 1990. Following the collapse of the Soviet Union in 1991, Hungary developed closer ties with Western Europe, as well as with other Central European countries, becoming a member of the Visegrad Group in 1991, and joined NATO in 1999 and the European Union on May 1, 2004.