The King's reign coincided with one of the greatest and swiftest periods of change in the history of Denmark. During these years, Danish society shook off the restrictions of an agricultural society marked by scarcity and developed at breakneck speed towards a welfare state characterised by abundance. Simultaneously, in the light of the experience gained from the Second World War, the former policy of neutrality was replaced by a policy of actively joining alliances. Furthermore, as a consequence of the booming economy of the 1960s, women entered the labour market and achieved in decisive areas the equality that their mothers and grandmothers had fought for over the years. In other words, Denmark became a modern country, which meant altogether new demands on the monarchy and its ability to adjust.
Tactfully supported by the Queen, King Frederik IX with a definite sense of the requirements of the day carried through the change of the monarchy from a distant, elevated institution to a general, symbolic image of the levelling out of class distinctions, which was a result of the modernisation of society.
The King's behaviour was cheerful and straightforward, and he possessed the gift of being able to deal with all people with natural friendliness and warmth without jeopardising the inherent dignity of a monarch. He was helped in this through his training as an officer of the navy with its binding but informal environment, which he felt strongly related to throughout his life. Before he became King, he had acquired the rank of Rear-Admiral and he had had several senior commands on active service. In addition, with his great love of music the King was an able piano player and conductor.
Due to the relaxed and loving tone in the Royal Family, which the King and Queen in contrast to previous tradition were prepared to give the public an idea of, the Royal Family in the reign of Frederik IX became a popular reflection of the typical Danish family as it developed in line with the modernisation of society. Shortly after the King had delivered his New Year's Address to the Nation at the 1971/72 turn of the year, he fell seriously ill. His death following a short period of illness was felt as a great loss by the Danish population, which to an unprecedented extent had taken the King and his family to heart.