Prince Srisiddhi Thongjaya, the Prince Siridhaj Sangkas (Thai: ศรีสิทธิธงไชย; RTGS: Si Sitthi Thongchai; 16 October 1857 – 11 March 1910) was a Prince of Siam. As a son of King Mongkut and Chao Chom Manda Bua,[1] he was a member of Siamese royal family.
His mother was a daughter of Chao Phraya Nakhon Noi, a son of King Taksin. He was given full name as Phra Chao Borom Wong Ther Phra Ong Chao Srisiddhi Thongjaya Krom Khun Siridhaj Sangkas (Thai: พระเจ้าบรมวงศ์เธอ พระองค์เจ้าศรีสิทธิธงไชย กรมขุนสิริธัชสังกาศ).
He had 4 siblings: 1 elder brother, 1 younger sister, and 2 younger brothers:
