The Bohemian poet John Sictor was born Jan Sictor Rokycanský (1593-1652). He was displaced during the Thirty Years War that pitted Protestants against Catholics. He moved to England and his name was anglicized to John. He wrote this chronogram ( meaning "time writing") with capital Roman numerals cleverly embedded in the words that provide the date of the Battle of Dunbar in 1650. This battle was fought during the English Civil War when Oliver Cromwell replaced the monarchy with the Protectorate. For more on chronograms, see Calendars and Time Keeping.
 William Poole, “Down and Out in Leiden and London: The Later Careers of Venceslaus Clemens (1589-1637), and Jan Sictor (1593-1652), Bohemian Exiles and Failing Poets,” The Seventeenth Century 28.2 (2013): 163-185; Robert Fitzgibbon Young, A Czech Humanist in London in the 17th Century: Jan Sictor Rokycanský(1593-1652) (London: School of Slavonic Studies in the University of London, King’s College, 1926).