[1][4][6] During the late 1970s, she and a growing number of New Zealanders rallied against the United States Government's policy of “neither confirming nor denying” the presence of nuclear warheads on their warships.

[9] Not long after, Dewes enrolled in a peace studies program at the University of Bradford, whilst juggling motherhood with a teaching career and a number of official positions and voluntary roles.

[10] The senior journalist, Mike Crean, in an interview with Dewes after her New Year Honour,[4] explored that idea that the strength of her feelings came from her ancestors; for she had only recently found out that not only did her paternal great-grandmother work for peace among the northern Hawkes Bay Māori in 1870, but also her maternal grandparents had campaigned for temperance and women's suffrage in the late 19th century.

[4] Dewes successfully lobbied for the world's first national nuclear-free laws, known as the New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act 1987.

[1][4][13] She subsequently completed her doctorate at the University of New England in Australia, with a thesis entitled The World Court Project: The Evolution and Impact of an Effective Citizens' Movement.