The 16th century work depicts a biblical massacre of children as a contemporary political attack. Bruegel, working when the Low Countries were under assault from Spain, paints the attacking troops as Spanish. But when the work was acquired by Rudolf II, Holy Roman Emperor, who was related to King Philip II of Spain, experts believe he had the slaughtered babies painted over. Desmond Shawe-Taylor, Surveyor of the Queen's Pictures, said: "He probably thought, 'I don't particularly like my cousin's troops massacring people.'"