[1] In 1913, while at Harvard, the New York Court of Appeals ruled that he was the legal heir of the $7,000,000 estate of Louis Carré Hamersley, his father's cousin who died in 1883.

[1] In 1914, Hamersley purchased the former John Armstrong Jr. estate in Dutchess County and erected a tudor revival mansion and gatehouse designed by Francis Hoppin.

[11] He expanded his estate, acquiring several farms to the north, and Maizeland on Cruger's Island in 1920, eventually owning what was described at one time as the second largest in Dutchess County.

[12] After Harvard, Hamersley went to the Mexican border with Battery A of the Massachusetts National Guard, followed by a post as an ambulance driver for the American Field Service in France.

[1] He was also a well-known speed boat pilot and, in 1925, he made a record run of 2 hours and 38 minutes from New York to Albany in his speedboat Cigarette Jr.