Thadeus Defrees was a Boston artist born in 1855. In 1878, he came up to Jackson, New Hampshire to take painting lessons from Frank Shapleigh, who was artist in residence at the Crawford House and who had a home in Jackson.
Defrees' style is Barbizon, presumably acquired looking at prints from Europe. His similarity to Shapleigh lies in the detail he painted on the rear of his White Mountain paintings in the manner of Shapleigh.
The only presently known, published reference is to be found in the White Mountain Echo and Tourist Register of August 23, 1884, page 16 (NH Historical Society) It says," Mr. T. Defrees, the Boston Artist, has been sojourning in Jackson during the past week, stealing some of the very fine views about that region."
Several of his signed oil paintings of the White Mountains dated 1880 are known to exist. Shapleigh advised him to go to Europe for further development. He went there and contracted a disease in Venice and died there in 1888.
Information courtesy of Sam Robbins
Death notice in White Mountain Echo, July 28, 1888