[3] His family's wealth allowed the young Davies to travel extensively to exotic locations, where he enjoyed game hunting.

In the First World War, he commanded the 14th Battalion of the Royal Welsh Fusiliers until 1916, when he was appointed Parliamentary Secretary to David Lloyd George.

In 1932, he established the New Commonwealth Society for "the promotion of international law and order," writing several books on the right use of force, notably The Problem of the Twentieth Century (1930), which was translated into German and other languages.

In 1910, he contributed £150,000 (£19.3 million as of 2025) to the King Edward VII Welsh National Memorial, which was formed with the aim of eradicating tuberculosis in Wales.

The Welsh Temple of Peace in Cardiff was his brainchild, and was funded by Davies, to a great extent, pledging £58,000 in 1934 (equivalent to £4.4 million in 2023[9]) towards the erection of a building.

In 1910, Davies married his first wife Amy Penman, daughter of Lancelot Tulip Penman of Broadwood Park, and had two children:[1] Four years after Amy's death in 1918, he remarried to Henrietta Margaret Fergusson, daughter of James Grant Fergusson of Baledmund, Perthshire, and had four more children:[1] In 1944, while launching a new X-Ray mobile scanning unit at Sully Hospital (which the Temple of Peace in Cardiff had funded), Davies volunteered to undergo the first routine chest scan.

David Michael Davies, was serving in the Royal Welsh Fusiliers when he was killed in action in September 1944, only a few months after inheriting the title.