Otto von Habsburg: Last Crown Prince of Austria-Hungary who later championed European unification

Otto von Habsburg was the eldest son of Austria-Hungary's last emperor and former heir to the imperial throne. He witnessed the dismantling of the empire his family had ruled for centuries, but emerged to carve out a career in politics and became a strong proponent of a united and democratic Europe.

Although Habsburg struggled in vain, while in exile, to make a stand against the Nazis annexing Austria before the Second World War and later fought against Communism, it was as president of the Pan-European League that he perhaps had his greatest impact on European events. Along with his Hungarian counterpart, Imre Pozsgay, he organised a peace protest, the Pan-European Picnic, near St Margarethen, Austria, and the town of Sopron in western Hungary on 19 August 1989. In a symbolic gesture agreed to by both countries, the border was opened for three hours and more than 600 East Germans fled to the West. This momentary penetration of the Iron Curtain became one of the events that hastened the fall of the Berlin Wall and the demise of Communism. Less than a month later, Hungary officially opened its western border for East Germans seeking to leave.

Habsburg was born in the Villa Wartholz in Reichenau an der Rax, Lower Austria, to Archduke Charles and Maria, former Princess Zita of Bourbon-Parma, during the 67-year reign of Emperor Franz Josef I, his great uncle. He was christened Franz Josef Otto Robert Maria Anton Karl Max Heinrich Sixtus Xavier Felix Renatus Ludwig Gaetan Pius Ignatius; it was suggested that the string of names was to illustrate that the blood of all the European Roman Catholic royal families ran through his veins.

With the assassination by a Serbian separatist of Archduke Franz Ferdinand of Austria, and heir apparent, in Sarajevo in June 1914, Habsburg's father became first in line to the throne. Weeks later, Europe entered a war that would see the disintegration of the Austro-Hungarian Empire. In November 1916, after ruling for almost 68 years, Franz Joseph died and Charles ascended to the throne with the toddler Otto becoming Crown Prince. Following defeat in the Great War, the Empire, with its diverse number of ethnic groups and languages, was broken up into smaller states, including Czechoslovakia and Hungary, with Austria becoming a republic.

In November 1918, Emperor Charles I, though not formally abdicating, "renounced participation in the affairs of state". In March 1919, the Habsburgs left for Switzerland escorted by the commander of a small British guard detachment, Lt. Col. Edward Strutt. The Austrian Parliament passed the Habsburg Law, which permanently barred Charles and Maria from returning to Austria, although they kept their personal fortune. After two failed attempts by Charles to regain his Hungarian crown, the family was exiled by the Allied powers to the Madeira, where Charles died in April 1922 – whereupon Habsburg, who was not yet 10, became the official head of the Habsburg family and pretender to four former thrones.

The family moved to the Basque country under the protection of King Alfonso XIII of Spain, where Habsburg studied hard, before uprooting again to attend the University of Louvain in Belgium, where he earned a doctorate in political and social sciences. Habsburg tried to negotiate his return to Austria in 1935 and again in 1938, when he sought to become chancellor to fight the expected Anschluss. However, he could not gather enough support and the pro-monarchist Austrian Chancellor Kurt Schuschnigg prevaricated before rejecting the plan. As a consequence of his opposition to Hitler, Habsburg was sentenced to death and placed high on the Gestapo's wanted list. Shortly before the Germans' arrival in Paris in May 1940, the family fled Portugal before arriving, with the help of President Roosevelt, in Washington DC, where they spent most of the Second World War. Habsburg worked with the White House in a vain attempt to persuade Hungary to join the Allies.

With the end of hostilities in Europe, the Habsburgs returned to Europe but were effectively stateless. Habsburg himself eventually secured a Spanish diplomatic passport and embarked upon a journalistic and lecturing career. In 1950, on a visit to Bavaria, he met Princess Regina of Sachsen-Meiningen, also a refugee who was working as a nurse. The couple married a year later and moved to Pöcking near Lake Starnberg in Bavaria. They had seven children, although it was not until their sixth, Karl Thomas, in January 1961, that the line of direct succession was guaranteed.

This seemed to be the catalyst Habsburg needed. In May, he renounced his own claims to the Austrian throne and announced that he was a loyal subject of the republic. This resulted in an Austrian court lifting the ban on him visiting the land of his birth. The decision proved unpopular in some quarters, particularly with the Socialists, and precipitated a crisis of state, later referred to as the "Habsburg crisis". He was eventually issued with an Austrian passport in October 1966, following elections in June which saw the People's Party win an outright majority.

Habsburg joined the Christian Social Union (CSU), the right-wing Bavarian sister party of the Christian Democratic Union party (CDU). In 1979, he was elected to the European Parliament, where he sat for 20 years, eventually becoming its oldest serving member, seen as "Father of the House". Perhaps, though, he always had one foot in the past: he was in parliament when someone mentioned a forthcoming football international – "Austria-Hungary", he was told. "Oh, who are they playing?" was his reply.

Fluent in seven languages, Habsburg proved a talented debater, but it appeared that his raison d'être was political union, bridging the East-West division and the eastward expansion of the EU to countries once ruled by his ancestors. His presidency of the International Pan-European Union, from 1973-2004, gave him a platform from which to further the cause.

Otto stopped appearing in public after the death of his wife, Regina, last year. He is survived by his younger brother, Felix, as well as seven children, 22 grandchildren and two great-grandchildren. His eldest son, Karl, ascends to head of the house of Habsburg.

Martin Childs

Franz Joseph Otto Robert Maria Anton Karl Max Heinrich Sixtus Xavier Felix Renatus Ludwig Gaetan Pius Ignatius von Habsburg, politician: born Reichenau an der Rax, Lower Austria 20 November 1912; married 1951 Princess Regina of Saxe-Meiningen (died 2010; five daughters, two sons); died Pöcking, Germany 4 July 2011.