The poem A la entrada del príncipe de Gales en Madrid por marzo del año 1623 (At the Entrance of the Prince of Wales in Madrid in March of the Year 1623) by Antonio de Solís, is a praise to the visit of the Prince of Wales to Spain in 1623. The purpose of the trip was to establish an alliance through a marriage with the daughter of Felipe III, the Infanta Maria Ana. The link was never held. The Spanish crown demanded the conversion of the Prince of Wales to Catholicism. Upon his return to England, Charles demanded that King James declare war against Spain.
Carlos’s trip to Madrid marked his interest in art. Felipe also gave him Spanish horses, which contributed to the emergence of purebreds in England.
(Description is in English, book edition is in Spanish)