He came from a line of wealthy rice traders and pharmacists who had immigrated from Hainan Province, China to reside in the largely mercantile Thonburi across the river from Bangkok.
Malaria proved to be a more formidable foe than the Haw and Thian Hee was largely occupied with administering quinine to afflicted troops.
A photograph now on view at Vimanmek Mansion depicts Thian Hee handing the last bottle of quinine to the commanding general to prove the scarcity of their supplies.
Among his activities in Laos as part of an occupational force was the imposition of a partially successful ban on the practice of using witch doctors and witchcraft to heal the local populace of illnesses.
He acted as a financial advisor to Queen Savang Vadhana, often serving as intermediary between the palace and the largely insular Chinese merchant community.