Viewed in terms of the number of European rulers who met violent deaths, the thirty or so years either side of 1600 might almost be termed the ‘Age of Assassination’. One major political figure after another succumbed to the assassin’s hand: the Duc de Guise in 1563; Henry, Lord Darnley (Mary Queen of Scots’ consort) in 1567; Henri III of France – last of the Valois kings – in 1589; Henri IV – the first of the Bourbons – in 1610; the Duke of Buckingham in 1628 – not to mention Guy Fawkes’s attempt to blow up James I and the entire English House of Lords in 1605.

In this catalogue of political murders, achieved and attempted, one particular monarchical demise stands out: the killing of Willem ‘the Silent’ – Prince of Orange, Count of Nassau, and Stadhouder (or ‘Protector’) of the Seventeen Provinces of the Habsburg Netherlands (roughly modern-day Belgium and the Netherlands) – by a Catholic