What if all sons of Queen Victoria died young? In this scenario her heir would be her oldest daughter and then her children. So Empress Frederick, so she was known after her husband's death in 1888, would become Queen Victoria II and after her death her son Emperor William II would become King William V uniting the United Kingdom and the German Empire under one crown. That would surely create a succession crisis in the UK, because no one in the UK would want a personal union between the United Kingdom and the German Empire.