Katherine Willoughby had two sons. On the 14th of July 1551 she lost them both in the same afternoon.

She was fourteen when she married Charles Brandon, Duke of Suffolk, a man thirty-five years her senior who had once been married to Henry VIII's own sister. The match made her one of the wealthiest women in England. It also made her sharp-tongued and unafraid of it, close to the reformist circle around Catherine Parr, reportedly bold enough to name a dog Gardiner after the conservative bishop she despised. By 1551 she was a widow, but she was not a quiet one. Her two sons, just fifteen and fourteen, Henry and Charles, were what remained of the Brandon line, and everything she had spent her marriage protecting ran through them.

That summer, sweating sickness broke out at Cambridge, where the boys were being educated, and it moved faster than anything the century had a name for. Contemporary chroniclers described people well at dinner and dead by supper, sometimes within two or three hours of the first symptom. Katherine had the boys moved to Buckden, to the Bishop of Lincoln's house, to get them clear of it. She fell ill herself during the move, and by the time she reached them, the sickness had already caught up with both her sons.

Their own tutor, Thomas Wilson, was in the house with them, close enough to the boys that he later wrote a book mourning their deaths, 'Vita et Obitus Duorum Fratrum Suffolciensium', Life and Death of the Two Suffolk Brothers. He watched them fail within hours of each other, Henry first, then Charles, alone in a separate room, dead half an hour after his brother, apparently without knowing his brother was already gone. Two boys who had shared a childhood, a household, a name, died minutes apart and out of each other's sight.

The requiem held for them that September did not soften what had happened. The mourners' language was blunt: so noble a stock was extinct in them. Charles had become Duke of Suffolk the instant his brother died, and held the title for less time than it takes to eat a meal. There was no one left after him.

She had spent her whole marriage protecting the Brandon name. It ended in one house, in two rooms, in half an hour.