Of the 77 children fathered by King Chulalongkorn, only seven sons born of queens survived beyond 1910, In the early 1920s, two of King Vajiravudh's three full brothers died. By the end of 1925, only the youngest brother, Prince Prajadhipok, was still alive. As a result, Wyatt writes that, "the problem of succession to the throne came to prominence rather suddenly in the last few years of the reign". This situation provided important impetus for drafting the Palace Law of Succession or "kot monthian ban wa duai kan suep santatiwong" in 1924. This law which continues to provide the framework for succession today, confirmed the primacy of the lineage of King Chulalongkorn and Queen Saovabha, as well as the king's sole and authentic right to choose his successor. It also made the determination of succession as legally precise and binding as possible.