Though Tono-Bungay was not a science-fiction novel, radioactive decay plays a small but consequential role in it. Radioactive decay plays a much larger role in The World Set Free (1914). This book contains what is surely his biggest prophetic "hit." Scientists of the day were well aware that the natural decay of radium releases energy at a slow rate over thousands of years. The rate of release is too slow to have practical utility, but the total amount released is huge. Wells's novel revolves around an (unspecified) invention that accelerates the process of radioactive decay, producing bombs that explode with no more than the force of ordinary high explosive but which "continue to explode" for days on end. "Nothing could have been more obvious to the people of the earlier twentieth century," he wrote, "than the rapidity with which war was becoming impossible... [but] they did not see it until the atomic bombs burst in their fumbling hands." Leó Szilárd acknowledged that the book inspired him to theorise the nuclear chain reaction.
Wells also wrote nonfiction. His bestselling two-volume work, The Outline of History (1920), began a new era of popularised world history. It received a mixed critical response from professional historians, but was praised by Arnold J. Toynbee as the best introductory history available. Many other authors followed with 'Outlines' of their own in other subjects. Wells reprised his Outline in 1922 with a much shorter popular work, A Short History of the World, and two long efforts, The Science of Life (1930) and The Work, Wealth and Happiness of Mankind (1931). The 'Outlines' became sufficiently common for James Thurber to parody the trend in his humorous essay, "An Outline of Scientists" indeed, Wells's Outline of History remains in print with a new 2005 edition, while A Short History of the World has been recently reedited (2006).
From quite early in his career, he sought a better way to organise society, and wrote a number of Utopian novels. Usually starting with the world rushing to catastrophe, until people realise a better way of living: whether by mysterious gases from a comet causing people to behave rationally (In the Days of the Comet), or a world council of scientists taking over, as in The Shape of Things to Come (1933, which he later adapted for the 1936 Alexander Korda film, Things to Come). This depicted, all too accurately, the impending World War, with cities being destroyed by aerial bombs. He also portrayed social reconstruction through the rise of fascist dictators in The Autocracy of Mr Parham (1930) and The Holy Terror (1939).
Wells contemplates the ideas of nature vs. nurture and questions humanity in books like The Island of Doctor Moreau. Not all his scientific romances ended in a happy Utopia, as the dystopian When the Sleeper Wakes (1899, rewritten as The Sleeper Awakes, 1910) shows. The Island of Doctor Moreau is even darker. The narrator, having been trapped on an island of animals vivisected (unsuccessfully) into human beings, eventually returns to England; like Gulliver on his return from the Houyhnhnms, he finds himself unable to shake off the perceptions of his fellow humans as barely civilised beasts, slowly reverting back to their animal natures.
Wells also wrote the preface for the first edition of W. N. P. Barbellion's diaries, The Journal of a Disappointed Man, published in 1919. Since "Barbellion" was the real author's pen-name, many reviewers believed Wells to have been the true author of the Journal; Wells always denied this, despite being full of praise for the diaries, but the rumours persisted until Barbellion's death later that year.
In 1927, Florence Deeks sued Wells for plagiarism, claiming that he had stolen much of the content of The Outline of History from a work, The Web, she had submitted to the Canadian Macmillan Company, but who held onto the manuscript for eight months before rejecting it. Despite numerous similarities in phrasing and factual errors, the court found Wells not guilty.
In 1934 Wells predicted that another world war would begin in 1940, a prediction which ultimately came true.
In 1936, before the Royal Institution of Great Britain, Wells called for the compilation of a constantly growing and changing World Encyclopaedia, to be reviewed by outstanding authorities and made accessible to every human being. In 1938, he published a collection of essays on the future organisation of knowledge and education, World Brain, including the essay, "The Idea of a Permanent World Encyclopaedia."
Near the end of the Second World War, Allied forces discovered that the SS had compiled lists of intellectuals and politicians slated for immediate liquidation upon the invasion of England in the abandoned Operation Sea Lion. The name "H. G. Wells" appeared high on the list for the "crime" of being a socialist. Wells, as president of the International PEN (Poets, Essayists, Novelists), had already angered the Nazis by overseeing the expulsion of the German PEN club from the international body in 1934 following the German PEN's refusal to admit non-Aryan writers to its membership.
Wells called his political views socialist. He was for a time a member of the socialist Fabian Society, but broke with them as he intended them to be an organisation far more radical than they wanted. He later grew staunchly critical of them as having a poor understanding of economics and educational reform. He ran as a Labour Party candidate for London University in the 1922 and 1923 general elections after the death of his friend W.H.R Rivers, but at that point his faith in the party was weak or uncertain.
His most consistent political ideal was the World State. He stated in his autobiography that from 1900 onward he considered a world-state inevitable. He envisioned the state to be a planned society that will advance science, end nationalism, and allow people to advance by merit rather than birth. During his work on the United Nations Charter, he opposed any mention of democracy. He feared the average citizen could never be educated or aware enough to decide major world issues. Therefore he favoured suffrage to be limited to scientists, organisers, engineers, and others of merit. On the other hand, he strongly believed citizens should have as much freedom as possible without restricting the freedom of others. These values came under increasing criticism from the 1920s and afterwards.
Lenin's attempts at reconstructing the shattered Russian economy, as his account of a visit (Russia in the Shadows; 1920) shows, also related towards that. This is because at first he believed Lenin might lead to the kind of planned world he envisioned. This was in spite of the fact that he was a strongly anti-Marxist socialist who would later state that it would've been better if Karl Marx was never born.
The leadership of Joseph Stalin led to a change in his view of the Soviet Union even though his initial impression of Stalin himself was mixed. He disliked what he saw as a narrow orthodoxy and obdurance to the facts in Stalin. However he did give him some praise saying in an article in the left-leaning New Statesman magazine, "I have never met a man more fair, candid, and honest" and making it clear that he felt the "sinister" image of Stalin was unfair or simply false. Nevertheless he judged Stalin's rule to be far too rigid, restrictive of independent thought, and blinkered to lead toward the Cosmopolis he hoped for.
In the end his contemporary political impact was limited. His efforts to help form the League of Nations became a disappointment as the organisation turned out to be a weak one unable to prevent World War II. The war itself increased the pessimistic side of his nature. In his last book Mind at the End of its Tether (1945) he considered the idea that humanity being replaced by another species might not be a bad idea. He also came to call the era "The age of frustration." He spent his final years venting this frustration at various targets which included a neighbour who erected a large sign to a servicemen's club. As he devoted his final decades toward causes which were largely rejected by contemporaries, this caused his literary reputation to decline. One critic said, "Mr. Wells is a born storyteller who has sold his birthright for a pot of message."
Wells, like many in his time, believed in the theory of eugenics. In 1904 he discussed a survey paper by Francis Galton, co-founder of eugenics, saying "I believe .. It is in the sterilisation of failure, and not in the selection of successes for breeding, that the possibility of an improvement of the human stock lies." Some contemporary supporters even suggested connections between the "degenerate" man-creatures portrayed in The Time Machine and Wells's eugenic beliefs. For example, this is what Irving Fisher, the economist, said in his 1912 presidential address to the Eugenics Research Association: "The Nordic race will... vanish or lose its dominance if, in fact, the whole human race does not sink so low as to become the prey, as H. G. Wells images, of some less degenerate animal!"
Wells, a diabetic, died of unspecified causes on 13 August 1946 at his home at 13 Hanover Terrace, Regent's Park, London, although some reports indicate the cause of death was diabetes or liver cancer. In his preface to the 1941 edition of The War in the Air, Wells had stated that his epitaph should be: "I told you so. You damned fools." but his wish was not granted as he was cremated on 16 Augus