to this day, 102 years ago, in the midst of WWI when Prince Arthur and Princess Alexandra of Connaught attended a society wedding, he in military uniform and she in a lovely picture hat.
Photo from Getty as indicated
Royal Hats
The Bold, Beautiful and Bizarre World of Royal Millinery
Royal Hats 
She was the daughter of the then Princess Royal, Princess Louise. She succeeded her father as Duchess of Fife in her own right, but unfortunately she and Prince Arthur had no children during their marriage.
The outfits shown were very evocative of WW1 styles.
Correction: They had a son Alastair who unfortunately died in 1943 aged 29.
Elegant couple! Alexandra’s Wikipedia listing is really interesting. She had a serious career in nursing, unusual for any women of her generation, but especially for a great-grandchild of Queen Victoria.