 In 1573 the King, Charles IX, and nine princes of the blood all signed a declaration assuring Charles' brother Henry, Duke of Anjou, who was about to assume the crown of Poland, that his rights to the French throne would not lapse, nor those of any children he may have, even though they were to be born outside France.The blood right in this instance overcame the law of aubain by which foreign-born heirs forfeited their rights of succession; that is to say, being "capable of the crown" was a unique kind of birthright which transcended all usual legal regulations.Blood heirs no matter where they were born or resided were to be regarded ""tout ainsi que s'ilz estoient originaires et regnicoles"."