Ryle was a new physics graduate and an experienced radio ham in 1939, when the Second World War started. He played an important part in the Allied war effort, working mainly in radar countermeasures. After the war, "He returned to Cambridge with a determination to devote himself to pure science, unalloyed by the taint of war."
In the 1970s, Ryle turned the greater part of his attention from astronomy to social and political issues which he considered to be more urgent. With publications from 1976 and continuing, despite illness until he died in 1984, he pursued a passionate and intensive program on the socially responsible use of science and technology. His main themes were:
* Warning the world of the horrific dangers of nuclear armaments, notably in his pamphlet Towards the Nuclear Holocaust.
* Criticism of nuclear power, as in Is there a case for nuclear power?
* Research and promotion of alternative energy and energy efficiency, as in Short-term Storage and Wind Power Availability.
* Calling for the responsible use of science and technology. "...we should strive to see how the vast resources now diverted towards the destruction of life are turned instead to the solution of the problems which both rich - but especially the poor - countries of the world now face."
In 1983 Ryle responded to a request from the President of the Pontifical Academy of Sciences for suggestions of topics to be discussed at a meeting on Science and Peace. Ryles reply was published posthumously in Martin Ryles Letter. An abridged version appears in New Scientist with the title Martin Ryles Last Testament'. The letter ends with "Our cleverness has grown prodigiously – but not our wisdom."