Somdet Chao Phraya Borom Maha Prayurawongse (Thai: สมเด็จเจ้าพระยาบรมมหาประยูรวงศ์; RTGS: Somdet Chao Phraya Borom Maha Prayurawong; 1788 - 26 April 1855) or Tish Bunnag (Thai: ดิศ บุนนาค; RTGS: Dit Bunnak) was a prominent political figure of Siam during the mid-19th century as a regent for King Mongkut kingdom-wide. He became a Somdet Chao Phraya — the highest rank a Siamese noble had attained during the Rattanakosin Era, with honor equal to that of royalty. He was known colloquially as Somdet Chao Phraya Ong Yai (Thai: สมเด็จเจ้าพระยาองค์ใหญ่). He was also known as Chao Phraya Phraklang (Thai: เจ้าพระยาพระคลัง), or Minister of Trade, and dominated Western affairs of Siam during the reign of King Rama III. He held the post of Samuha Kalahom (Thai: สมุหกลาโหม), the Prime Minister of Southe