With the advent of the
Balkan Wars, Prince Andrew was reinstated to the army and Princess Andrew acted as a nurse, assisting at operations and setting up field hospitals, for which work George V awarded her the
Royal Red Cross in 1913. During
World War I, her brother-in-law,
King Constantine of Greece, followed a neutrality policy despite the democratically elected Government of Venizelos supporting the
Allies. Princess Andrew and her children were forced to shelter in the palace cellars during the French bombardment of Athens on
1 December 1916. By June 1917, the King's neutrality policy had become so untenable that she and other members of the Greek royal family were forced into exile when her brother-in-law abdicated. For the next few years most of the Greek royal family lived in
Switzerland.
The global war effectively ended much of the political power of Europe's dynasties. The naval career of her father, Prince Louis of Battenberg, had collapsed at the beginning of the war in the face of anti-German sentiment in Britain. At the request of King George V, on
14 July 1917, he relinquished the title Prince of Battenberg in the Grand Duchy of Hesse and the style
Serene Highness, and Anglicized the family name to Mountbatten. The following day, the King created him
Marquess of Milford Haven in the
peerage of the United Kingdom. The following year, two of her aunts,
Alix, Tsarina of Russia and
Grand Duchess Elizabeth Fyodorovna were murdered by
Bolsheviks after the
Russian revolution. At the end of the war the Russian, German and
Austro-Hungarian empires had fallen, and Princess Andrew's uncle,
Ernest Louis, Grand Duke of Hesse was deposed.
On King Constantine's restoration in 1920, they briefly returned to Greece, taking up residence at Mon Repos in
Corfu. But after the defeat of the
Hellenic Army in the
Greco-Turkish War, a Revolutionary Committee under the leadership of
Syntagmatarkhis (
Colonel) Nikolaos Plastiras and Syntagmatarkhis
Stylianos Gonatas seized power and forced King Constantine into exile once again. Prince Andrew, who had served as commander of the Second Army Corps during the war, was arrested. Several former ministers and generals arrested at the same time were shot, and British diplomats assumed that Prince Andrew was also in mortal danger. After a show trial he was sentenced to banishment, and Prince and Princess Andrew and their children fled Greece aboard a British cruiser,
HMS Calypso, under the protection of the British naval attaché, Commander Gerald Talbot.
The family settled in a small house loaned to them by
Princess George of Greece at
Saint-Cloud, on the outskirts of
Paris, where the princess helped in a charity shop for Greek refugees. She became deeply religious, and on
20 October 1928 entered the
Greek Orthodox Church. That winter, she translated her husband's defence of his actions during the Greco-Turkish War into English. Soon afterward, she began claiming that she was receiving divine messages, and that she had healing powers. In 1930, after suffering a severe nervous breakdown, Princess Andrew was diagnosed with paranoid
schizophrenia at Dr Ernst Simmel's sanatorium at
Tegel, Berlin. She was forcibly removed from her family and placed in Dr
Ludwig Binswanger's sanatorium in
Kreuzlingen, Switzerland. It was a famous and well-respected institution with several celebrity patients, including
Vaslav Nijinsky, the ballet dancer and choreographer, who was there at the same time as Princess Andrew.
During Princess Andrew's long convalescence, she and Prince Andrew drifted apart, her daughters all married German princes between 1930 and 1931 (she did not attend any of the weddings), and Prince Philip went to England to stay with his uncles,
Lord Louis Mountbatten and
George Mountbatten, 2nd Marquess of Milford Haven, and his grandmother, the Dowager
Marchioness of Milford Haven.
She remained at Kreuzlingen for two years, but after a brief stay at a clinic in
Merano, was released and began an itinerant, incognito existence in Central Europe. She maintained contact with her mother, but broke off ties to the rest of her family until the end of 1936. In 1937 her daughter Cécile, son-in-law and two of her grandchildren were killed in an
air accident at Ostend, she and Prince Andrew met for the first time in six years at the funeral (Prince Philip, Louis Mountbatten and
Hermann Göring also attended). Henceforth, she remained in contact with her family, who welcomed her gradual return to "normalcy". In 1938, she returned to Athens alone to work with the poor, living in a two-bedroomed flat near the
Benaki Museum. She attempted to resume maternal responsibility toward her teen-aged son, welcoming his visit to Athens and explaining to her brother why she felt he should now re-patriate to Greece, apparently oblivious to the facts that Louis had already introduced him to his future wife and was steering him toward a future in Britain's service.