William I, 'the Conqueror' (1028–1087), became King of England in 1066 after a series of dramatic military victories over his rivals. As a result, early depictions almost always show him in full military garb, his armour acting as shorthand for his achievements on the battlefield. This print is no exception, and when published in 1597 in A Booke Containing the True Portraiture of the Kings of England, the text described William as a most 'warlike & politick prince'. 

The print may have influenced a number of painted portraits of William the Conqueror, with the king's armour crucial in creating a quickly recognisable figure. The armour is however drawn from several different eras, and none is from the period in which William actually lived: a sixteenth-century falchion (one-handed sword) has been combined with fanciful Greco-Roman forms.  The classical elements were perhaps intended to make the king resemble Mars, Roman God of War.