Prince Mahidol was the 69th child of King Chulalongkorn. In 1905, he was sent to England, where he enrolled at Harrow School for a year and a half. He then moved to Germany, where he attended the Royal Prussian Military Preparatory College at Potsdam, the Imperial Military Academy at Gross Lichterfelde in Berlin and the Mürwik Imperial German Naval Academy at Flensburg, where he won a competition in submarine design. He returned to Thailand in 1914 when WWI started.
Around 1917, Prince Mahidol decided to study Public Health at Harvard University and asked his older half-brother, Prince Rangsit, to select four Thai students to receive a scholarship to join him in Cambridge, MA: two male students to study medicine and two female nursing students. One of the nursing students selected was Sangwal Talabhat. She travelled first to Berkeley, California, where she studied for a year at Emerson School and lived with a local family. Then in 1918, she travelled to Massachusetts, where Prince Mahidol met the Thai students at the train station. Sangwal did not know who he was, but his first impression, which he woke up his roommate to share, was “The two girls have arrived. Sangwal is really very pretty, you know.” Sangwal was enrolled at North Western Grammar School in Hartford, Connecticut, where she lived with a local family again. In 1919, Mahidol proposed to Sangwal and she moved to Cambridge, where she lived with another family and received tutoring in algebra, Latin, French, English and art history. They were married in 1920 and Mahidol received his Certificate in Public Health in 1921, while Sangwal studied nursing at Simmons College and school health at MIT.
The couple lived in the United Kingdom, Thailand and Germany before returning to Massachusetts. Mahidol received his medical degree (with honors) from Harvard in 1927 or 1928. He practiced medicine in a missionary hospital in Chiang Mai, Thailand, where he was known as “Doctor Prince”, but died at age 37. Sangwal survived until the age of 94. Two of their sons went on to become King of Thailand, and Sangwal served for a time as Regent to their son Bhumibol. She also supported education and public health projects and was a very popular public figure.
[thanks to qbqrat for the tip!]