The clinching English victory never came. Instead of bonfires lighting English celebrations, and great guns informing the countryside of English victories the following summer brought with it the flames of English men-of-war fired in the Medway by the Dutch navy and the sounds of Dutch guns bombarding the English coast. What had happened? Why did the English, who had seemed to be on the threshold of a total victory over the Dutch and their allies in the autumn of 1666, suffer such an ignominious defeat at the hands of the Dutch republican leader John De Witt the following summer?

At the exact moment in which English hopes for victory were being widely expressed, they received a damaging blow in the Netherlands. In early August 1666 the English government's chief Orangist agent, the Sieur de Buat, mistakenly delivered to John De Witt a letter from Arlington which “enlightened” De Witt as to “the design of promoting the sovereignty of the Prince of Orange, and of the constraining of the States to conclude a peace to the betraying of their liberties.” Buat was quickly incarcerated, brought to trial and ultimately beheaded for his treason. At his trial, Buat claimed – and the States General did everything to publicize Buat's statements in his own defense – that “what he did was with a good intention,” an intention to “make the King of England the greatest monarch in the world.”