He was the 16th prime minister of Luxembourg, serving for sixteen years, from 5 November 1937 until his death, on 23 December 1953, and was also responsible at different times for the ministries of finance, the army, agriculture, labour and social matters.

Once in Bordeaux, they were granted transit visas from the Portuguese consul Aristides de Sousa Mendes, in June 1940.

[2] Pierre Dupong, along with his wife Sophie, and their children Marie Thérèse, Lambert Henri, Henriette and Jean, followed the Grand Ducal family through Coimbra and Lisbon, settling at Praia das Maçãs after the Grand Ducal family had moved to Cascais.

The Dupong couple stayed at Chalet Posser de Andrade until 26 September 1940, while their children remained there until 2 October 1940.

He is also notable for sending Luxembourgish soldiers in the UN mission during the Korean War, as part of the Belgian United Nations Command.