Wilhelm II and the failure of royal family diplomacy

Which grandson undermined Queen Victoria's dynastic peace strategy?

Kaiser Wilhelm II is identified, with the First World War and the subsequent collapse of monarchies treated as consequences of the failure.

Wilhelm II is singled out when the discussion asks whether any one individual can be blamed for the First World War. This connects Queen Victoria's family diplomacy with a grandson whose decisions helped undermine it. The war contributed to the loss of many European monarchies. Their decline is judged likely to have happened eventually, but a slower change or a transition towards constitutional monarchy remains a possible alternative.