370 years ago, in January 1649, Charles I was charged with high treason and executed at Whitehall, in front of « his people ». And yet, his death was the beginning of a new era. On the very day of his execution, the book Eikon Basilike was published. This collaborative work helped to create the king's new portrait : being a father and a man rather than « God's lieutenant on earth ». But there is more to consider : readers should be seen as actors and co-creators of this new image. The reception of the text is central to understand the transformations the British monarchy was about to experience. This popular version of the king was a revolutionnary way to represent royal authoriy and a powerful way to conquer the subjects' hearts. Royalists had already understood that new means of communication meant new strategies, such as creating empathy, appealing to emotions, strengthening the link between authors and readers. But here, we argue that « people make kings » : we usually called Eikon Basilike « the King's book ». But since readers quickly appropriated the book, it became the « people's book ». Charles I intended to die for monarchy but, in doing so, he (and his counsellors) created a new and modern form of monarchy. In the seventeenth century, the main issues were struggles for sovereignty and power : Eikon Basilike is a good example. To win the battle, the royalists invited people to participate in this redefinition of sovereignty. To go further, it is essential to focus on the way people appropriated the book but also on its materiality (sizes, bindings, illustrations, additional material, annotations and marks) and the objects surrounding the cult of Charles the Martyr. Thanks to changing words and imagery, 1649 garanteed the continuity and stability-and evolution-of the British monarchy, allowing people to represent, even create, their « own king » and reinvent monarchy.