Young adulthood
In 1927, Sophie met one of her distant cousins, Prince Philipp of Hesse-Kassel. Shortly after, she met two of his brothers, the twins Christoph and Richard of Hesse-Kassel at Schloss Hemmelmark, the home of her great-aunt Princess Irene of Hesse and by Rhine. Despite her being 13 years their junior, the two German princes soon attempted to court her and it was Christoph who managed to grab her attention. Their romance eventually ended in an engagement, which was officially celebrated when Sophie turned 16, in 1930. Around the same time, Cecilie, Sophie's favorite sister, became engaged to another member of the House of Hesse, Georg Donatus, Hereditary Grand Duke of Hesse.
The happiness of the princess was however clouded by the situation of her mother, whose mental health deteriorated sharply after the celebration of her silver wedding anniversary with Prince Andrew, in 1928. Struck by a mental health crisis, the princess convinced herself that she possessed healing powers and that she was receiving divine messages about potential husbands for her daughters. She then took herself for a saint and soon declared herself the bride of Jesus. Distraught by the situation, Prince Andrew finally made the decision to place his wife in a sanatorium. He took advantage of his family's stay in Darmstadt, on the occasion of the celebration for Cecilie's official engagement in April 1930, to send Alice to a psychiatric hospital located in Kreuzlingen, Switzerland.
In the absence of their mother, Sophie and Cecilie made their wedding preparations together. The two princesses thus went to London, in the spring of 1930, in order to obtain new clothes. Shortly after, they returned to Paris to put together their trousseau and buy their wedding dresses. The nuptials of Sophie and Christoph were celebrated in Kronberg im Taunus on 15 December 1930. They were married in two religious ceremonies, with the Orthodox one held at Friedrichshof Castle, owned by her mother-in-law Princess Margaret of Prussia, and the Lutheran one at a church in the city. A few weeks later, on 2 February 1931, Cecilie and Georg Donatus married in the presence of their family at the Neue Palais in Darmstadt.
With their honeymoon over, Sophie and Christoph moved into an apartment in Berlin's Schöneberg quarter. After working for a long time in the Maybach car factory in Friedrichshafen, the prince had just been hired as a broker by the Victoria insurance company. While the princess moved to Germany to start a family, Greece went through a tumultuous political period, marked by numerous coups d'état. Confronted with permanent instability, the population gradually lost confidence in the institutions of the Hellenic Republic and King George II (Sophie's cousin) was finally reinstalled on the throne in November 1935.
In October 1930, Prince August Wilhelm of Prussia, son of Kaiser Wilhelm II, introduced his cousin Christoph to the politician Hermann Göring, and it did not take long for the two to form a closer relationship. Under the influence of Göring, the prince and his wife then met Adolf Hitler, who deceived them with his charm and his apparent modesty. Under these conditions, Christoph joined the Nazi Party, first secretly in 1931, and then publicly in 1933. He also joined the SS in February 1932. However, in his family, Christoph was not an exceptional case. His older brother Philipp had become a member of the Nazi Party in 1930. Subsequently, their respective twins, Princes Wolfgang and Richard of Hesse-Kassel, joined the party in 1932. Finally, their parents, Frederick Charles, Landgrave of Hesse and Princess Margaret, followed the example of their sons in May 1938.
Unlike her sisters Cecilie and Margarita, who joined the Nazi Party at the same time as their husbands in 1937, Sophie never became a member of the Nazi Party. Like her sisters-in-law, Princess Mafalda and Princess Marie Alexandra, she nevertheless joined the National Socialist Women's League in 1938. In fact, Sophie had long shown enthusiasm for Nazi Germany. Linked to the elite of the Hitler regime, the princess thus maintained friendly relations with Emmy Sonnemann, and was one of the guests of honor at the time of her marriage in April 1935 to Hermann Göring, who notably had Adolf Hitler as a witness.
From a financial point of view, the coming to power of Adolf Hitler significantly improved the situation of Christoph and Sophie. In 1933, the prince was appointed personal advisor to State Secretary to the Prussian State Ministry Paul Körner. Two years later, Göring placed Christoph in charge of the Forschungsamt, an intelligence service responsible for spying on the telecommunications of Nazi Germany. Under these conditions, Sophie and her husband left their old apartment for a new one in 1933, before moving into a large red brick villa located in Dahlem in 1936.
At the same time as these events, Sophie and Christoph's family grew larger with the successive births of Christina (1933–2011), Dorothea (1934–2025), Karl (1937–2022), and Rainer of Hesse (born 1939). The birth of their eldest son was also an opportunity for the couple to underline their support for Nazism, since the child received, among his names, that of Adolf, in tribute to the Adolf Hitler. Sophie also continued to worry about the fate of her mother Alice, whom she visited several times during the latter's confinement in Kreuzlingen between 1930 and 1933. Sophie also happily attended the weddings of her two eldest sisters, Margarita and Theodora, to German princes Gottfried, Prince of Hohenlohe-Langenburg and Berthold, Margrave of Baden in 1931. She was also present at the funeral of her sister Cecilie and her family, who were killed in a plane crash in 1937.
Sophie and Christoph also maintained their ties to their foreign relatives. The princess made several visits to the United Kingdom, and also stayed in Italy (1936) and Yugoslavia (1939). According to historian Jonathan Petropoulos, their travels were an opportunity for the couple to carry out, for the benefit of the Nazi Germany, a parallel diplomacy with their European cousins, such as Prince Paul of Yugoslavia and his wife Princess Olga of Greece and Denmark.
As a means of protection, Christoph warned Sophie about the need to beware of prying ears and never to speak politics with people other than her sisters and cousins. Even though he probably moved away from the SS from 1934, the prince nonetheless remained a staunch supporter of the Nazi regime. When Germany invaded Poland in September 1939, he spontaneously enlisted in the Luftwaffe, while retaining his post as director of the Forschungsamt. Sophie and her four children then left Berlin to settle in Friedrichshof, near her husband's parents the Landgrave and the Landgravine of Hesse. Then began a close correspondence between the couple, which testified to the love that Sophie and her husband had for each other.
Shortly after Sophie moved to Kronberg im Taunus on 28 May 1940, her father-in-law died in Wilhelmshöhe, making his eldest surviving son Philipp the new head of the House of Hesse-Kassel. At the same time, most of Europe fell under Nazi rule and Sophie's parents found themselves isolated far from their children. After the invasion of France, Prince Andrew was stuck on the French Riviera in June 1940. For her part, Princess Alice chose to stay in Athens despite the occupation of Greece and the departure into exile of other members of the Greek royal family in April 1941. This did not prevent Sophie from continuing to support the Nazi regime, as illustrated by the continuation of her visits to Emmy and Hermann Göring.
The situation changed from 1942 as the Nazi authorities began to distance themselves from the German aristocracy. In January and October 1943, Princes Wolfgang and Richard of Hesse-Kassel were successively dismissed from the army, without being threatened by the Nazi regime. In April, Hitler placed Landgrave Philipp under house arrest, before having him confined in the Flossenbürg camp after Italy's surrender to the Allies on 8 September 1943. A few days later, on 22 September, it was Philipp's wife, Mafalda's turn to be arrested. After two weeks of interrogation, Mafalda, who was the daughter of King Victor Emmanuel III of Italy, was imprisoned in Buchenwald, where she died on 27 August 1944, after being seriously wounded following an aerial bombardment. At the same time, searches were carried out by Obergruppenführer Josias, Hereditary Prince of Waldeck and Pyrmont, in the residences of Philipp and his mother. All these events led Sophie to open her eyes completely to the true nature of the Nazi regime.
The tragedies of the House of Hesse-Kassel did not end there, however. On 7 October 1943, Prince Christoph died under mysterious circumstances during a plane crash in the Apennine Mountains, near Forlì. A few months later, Princess Marie Alexandra of Baden (wife of Wolfgang) perished buried during an air-raid on Frankfurt am Main on 29–30 January 1944. Widowed and pregnant with her fifth child (Princess Clarissa, who was born on 6 February 1944), Sophie therefore found herself in a precarious situation, with her mother-in-law, Landgravine Margaret as her main support. Tired and emaciated, the princess was now responsible for bringing up her children on her own, while also taking care of Philipp and Mafalda's four children.
As Christoph's death was not made public by the Nazi regime, Sophie published a simple death notice for her husband in the Völkischer Beobachter on 18 October 1943. A few weeks later, in November 1943, the princess and her mother-in-law received a visit from Obergruppenführer Siegfried Taubert, commissioned by Heinrich Himmler to discreetly spy on the family. Aware of their vulnerability, the two women then refrained from expressing doubts about the conditions surrounding Christoph's death. Eager to know more about the fate of Philipp and Mafalda, Sophie tried, on the other hand, to obtain information from Emmy Göring, without success. At the same time, several relatives of the princess visited Friedrichshof, including her mother, Princess Alice, who managed to obtain a pass for Germany at the end of January 1944 and stayed with her daughter until April. Other relatives, including her brother-in-law Wolfgang and their cousin Prince August Wilhelm of Prussia arrived at the castle in February 1945.
