[1] He received a teaching certificate in 1914 and then attended courses on economics and foreign languages in Copenhagen.
[1] Between July 1940 and July 1941 he was the minister of justice in the cabinet led by Prime Minister Thorvald Stauning, but he had to resign when during a football match between the Danish and Austrian teams on Denmark's Constitution Day, 5 June, the Danish people attacked German soldiers with rocks and bottles.
[1] In 1945 he became the deputy chairman of the party's parliamentary group and was a close adviser to Knud Kristensen.
[3][5] He was named the director of the Mortgage Bank in 1948, but was reappointed minister of defence to the cabinet led by Erik Eriksen in 1950 and was in office until 1953.
[3][6] When the government resigned following the elections in September 1953 Petersen returned to the Mortgage Bank as director where he worked until 1964.