In mid-May 1395, Philippe de Mézières writes a Letter to king Richard II of England, an urgent call, which does not belong to the epistolary but to the allegorical and the mirror for princes genre. This letter, revealing a clear similarity of thought between the author and the king of France, Charles VI, to whose education the former contributed, is preserved as a unique manuscript, the Royal 20 B VI, in the British Library. This manuscript turns out to be the one offered to the English monarch and, being addressed to the latter, ended up in the hands of a prince, who was particularly able to appreciate its meaning and all its wit. Although Mézières advocates a reconciliation between the kings of France and England, to be sealed with a marriage between Isabelle de Valois, the former’s oldest daughter and the latter, which was the safest way to achieve his ultimate aim of a reconciliation within the Church and the re-conquest of the Holy Land, what he truly hoped for was the founding of the Order of the Passion of Jesus Christ.