Wars have many economic, political and social consequences. From changes to technology, to the re-drawing of borders, to mass losses of life, conflicts shape human history. They are also extremely challenging to predict – both in terms of their causes and effects.
Conflicts are consequential, but their consequences are often unpredictable. Major wars are often seen as turning points that bookend specific historical periods with distinctive geopolitical and technological contexts. So, it is natural to look ahead and try to identify the coming seismic shifts.
One of the lessons of history is that effective description does not lead to accurate prediction. Even so, it is still useful to look back at some of the well-known geopolitical, economic and technological turning points associated with war, to understand what this might mean for the future of conflict and its consequences.
Although President Trump claims to have ended seven or eight wars, there are plenty more for him to settle. According to the Upsala Conflict Data Program (UCDP), the number of state-based armed conflicts increased from 33 cases in 2013 to 61 in 2024, spread across 36 countries.
Figure 1. Number of state-based armed conflicts, 1946-2024
Source: UCDP/PRIO Armed Conflict Dataset
Note: ‘Internationalised intrastate’ conflict refers to scenarios where side A is always a government; side B is always one or more rebel groups; and there is involvement of foreign governments with troops.
In addition to the high-profile wars in Ukraine and the Middle East, there are numerous less well-known conflicts in Sudan and in other Sahel states. UCDP also count 74 cases of large-scale non-state violence, such as the gang violence in Haiti, and 49 cases of one-sided conflicts. These are mainly local, but many hostilities – China and Taiwan or India and Pakistan, among others – could be flashpoints that escalate into more general conflicts.
The fault lines are there, and countries are preparing for the earthquake by increasing their military spending and preparing for long wars. Even so, it is unclear whether this will make the quake less likely. Research by Efraim Benmelech and Joao Monteiro examines the relationship between military expenditure and conflict using a dataset on armed conflict and military spending for 161 countries over 75 years (from 1948 onwards). They find that even large increases in military spending produce only modest reductions in conflict risk, despite sharply raising the expected cost of war.
Wars as geopolitical punctuation marks
The historian, Eric Hobsbawm, labelled the period that began with the French Revolution in 1789 and ended with the outbreak of World War 1 in 1914 as ‘the long nineteenth century’. During this timeframe, economies were transformed by the diffusion of new technology from the industrial revolution, and the geopolitical landscape shifted with the development of Britain’s status as an economic and naval superpower. European wars were few and short, and the world became increasingly globalised.
Despite the Anglo-German naval arms race of the early 20th century, the onset and length of World War I in August 1914 were unexpected. Even the bond markets, those sensitive indicators of geo-economic tension, did not ‘anticipate’ war until over three weeks after the assassination of Archduke Ferdinand (Ferguson, 2006). The celebrated economist, John Maynard Keynes, arranged his investments on the assumption that there would be no war. Even after the war began, famously many people expected it to be over by Christmas.
After 1918, there were probably few people in Britain who thought of themselves as living in the ‘inter-war period’. Rather, they felt that what they called The Great War had been ‘the war to end all wars’. An exception may be Keynes. In his 1919 paper, The Economic Consequences of the Peace, he mourned the loss of the globalised world of 1914. It would not achieve the same level of openness for almost three-quarters of a century.
He also denounced the punitive ‘peace’ terms imposed by the Treaty of Versailles, whose economic effects made another war very likely – the victors inviting their own destruction. But he remained sceptical of people’s ability to predict the future. Indeed, towards the end of the book he argues that “the events of the coming year will not be shaped by the deliberate acts of statesmen, but by the hidden currents, flowing continually beneath the surface of political history, of which no one can predict the outcome”.
The inter-war period – running from 1918 to 1939 – was one of economic turbulence. The world lacked a dominant economic organising power, with Britain unable and the United States unwilling to take charge. After World War 2 came the Cold War, where the world became crudely divided between capitalism and communism. In essence, the capitalist part was organised by the United States and the Bretton Woods institutions (including the World Bank and IMF), which had been designed to prevent the turbulence of the inter-war period. For Eric Hobsbawm, the long nineteenth century was followed by a ‘short twentieth century’. It many ways it began in 1914 and ended in 1991 – not with war but with the demise of the Soviet Union. Even so, this judgement may be premature.
Wars as spurs to innovation
Major wars are not only geopolitical turning points but also remove obstacles to innovation. This gives them the potential to be times of technological transformation. Drone warfare has advanced more rapidly during the two years of Ukrainian conflict than in 20 years of US government-backed R&D. The pressure of combat speeds up arms races as evaluation of safety and reliability is streamlined, and moral and ethical issues are sidelined in favour of rapid product delivery.
The pressure to innovate applies not just to lethal weapons. The canning process was invented after prolonged research by Nicolas Appert of France in 1809, in response to Napolean needing a way of preserving food for his army and navy. It was many years later that the can-opener was invented, with soldiers using their bayonets in the first instance.
Many medical advances have also come from the experience of war, where the need to treat large numbers of wounded patients prompted experiment and innovation. For example, wars saw big improvements in wound debridement, prosthetic limbs and plastic surgery, as well as the mass production of penicillin during World War 2.
Manufacturing has also tended to change during periods of conflict. Process innovations, such as interchangeable parts and mass production, were actually introduced in UK naval arsenals and US gun manufacturers before being adopted by Henry Ford. The division of labour has its roots in the business of warfare.
The importance of military procurement for technology development prompted Vernon Ruttan to ask ‘Is War Necessary for Economic Growth?’. Writing at the turn of the century, he argued that war and the threat of war would be a less powerful inducement to technical change in the first half of the 21st century than it was during the last half of the 20th century. Whether or not his forecast proves correct, innovation does continue without war, and in many areas, civilian technology is well ahead of the military. This is partly because of the slowness of the military procurement process (compared with the short life-cycles of generations of electronics, for example).
Even areas like cryptography, once the preserve of military and spooks, have become dominated by commercial applications. A spin-off from military research, DARPA (the US Defense Advanced Projects Research Agency) developed the internet, and a spin-off from scientific research CERN (the European Organisation for Nuclear Research) developed the World Wide Web. While GPS was originally a military system, civilian use generated a range of complementary systems – many of which are now used by the military.
Perhaps it is not surprising that defence R&D is a major source of innovation. It is the largest component of publicly funded R&D in many countries, including the United States, the UK and France. If those resources had been spent on civil R&D – without the secrecy restrictions and diversion of scarce scientific and technical skills to the military – there may have been even more ‘innovations’. As an example of the effect of secrecy, the RSA public key cryptosystem – a method for data encryption – was discovered by Clifford Cocks at GCHQ in 1973 but was kept secret. It was then re-discovered independently by Ron Rivest, Adi Shamir and Leonard Adleman of MIT, by whose initials it is known, in 1977.
Forecasting war
Given the importance of such turning points, it is tempting to try and forecast the coming conflicts and their geopolitical and technological consequences. But as Lawrence Freedman demonstrates in The Future of War: A History, we are very bad at predicting the form of future conflicts. Some of the most perceptive analysts of war have been unfortunately overtaken by events.
Immanuel Kant’s 1795 book, Perpetual Peace: A Philosophical Essay, argues that republican governments would be more inclined to promote peace and commerce, and that a union of such states could promote pacifism. Despite being followed by the Napoleonic wars, the argument remains influential and is echoed by the ‘Democratic (or Capitalist) Peace’ hypothesis, that democratic and open-market states do not tend to fight each other.
Norman Angell’s 1910 book, The Great Illusion, points out that economic integration and the cost and destructiveness of modern weapons made war so expensive that no country could gain from starting one. Although he argues that war was unprofitable rather than impossible, the book is seen by some as an incorrect forecast. While he was correct about the expense and destruction involved, that did not stop World War 1. Governments do not always understand or act in their country’s best economic interests, after all.
While World War 2 was not as unexpected as World War 1, expectations about the effects of technology, particularly about the effects of bombing, proved wrong. It was physically more destructive than predicted, but, with the exception of the atomic bomb, strategically less decisive.
The atomic bomb shaped much Cold War prediction. The black humour of Dr Strangelove and Tom Lehrer reflected widespread perceptions of likely nuclear proliferation and Armageddon. By the 1960s, new nuclear powers arrived about every five years: the United States in 1945, Russia in 1949, the UK in 1952, France in 1960, and China in 1964. Optimists – hoping the trend would continue – expected about 17 nuclear powers by 2025. Pessimists – assuming that every country that could build a nuclear weapon would – expected about 50 nuclear powers by 2025. Both groups would be astonished to know that there are now only nine nuclear powers (see Figure 2), and that three Soviet republics – Ukraine, Belarus and Kazakhstan – surrendered their nuclear weapons.
Figure 2. Total inventory of nuclear warhead stockpiles, 1946-2024
Source: SIPRI Yearbook 2025 & Federation of American Scientists (FAS)
Note: Global historical data for nuclear warhead stockpiles (1946–2024) were sourced from the Federation of American Scientists (FAS). 2024 country-specific inventory data were obtained from the SIPRI Yearbook. This methodology results in a minor variance between the aggregated 2024 FAS figure and the sum of the SIPRI country inventories.
In his 2011 book, The Better Angels of Our Nature, Steven Pinker presents data to argue that violence has declined around the world, although he did not claim the trend was inevitable. Even so, given the current prevalence of conflict, he is in danger of suffering the same fate as Norman Angell and being remembered for an incorrect forecast.
The size distribution of wars, like that of earthquakes, is ‘fat-tailed’ – characterised by rare but extreme events. The fact that there have only been minor rumbles recently does not necessarily mean that the big one is not coming. There are reasons to be cheerful; there is less nuclear proliferation than expected, the Soviet Union departed peacefully, and World War 3 has not yet arrived.
Where can I find out more?
Because of the pace of events, commentary from think tanks is often the most effective source: