The Crown Prince of Thailand (or Siam; Thai: สยามมกุฎราชกุมาร; rtgs: Sayammakutratchakuman) is a title held by the heir apparent to the Thai throne. First created by King Chulalongkorn (Rama V) in 1886, for his son Prince Maha Vajirunhis, the king's eldest son by a royal wife Queen Savang Vadhana. Prior to this, the Siamese throne did not have a law or formal system regulating the royal succession. In 1688 King Petracha of Ayutthaya created the title of Front Palace, which by the Rattanakosin period had become the main title granted to the heir presumptive to the throne. However few Front Palaces have succeeded to the throne this way, with the exception of King Buddha Loetla Nabhalai (Rama II) in 1809. After the Front Palace crisis in 1875, the title of Front Palace was abolished and repla