This year marks the anniversary of two significant events from the last century, perhaps the most significant of any century: 100 years since the outbreak of the First World War and 75 years since the start of the Second World War. It is natural for specialist publications to search out a ‘local’ angle on major news events, and Nature is no different. When it comes to modern warfare, however, the task is easier than with most events, for science is not a tangential topic in armed conflict. It lies, for both good and evil, at its heart.

We live, said Martin Luther King, in an age of guided missiles and misguided men. Scientists can do little about the latter (although we must still try), whereas the former shows the contradictions of military research in all its shades of grey. If we are to kill people, then is it a good thing that we are able to target them more precisely? The death of one becomes more likely; the deaths of others less so.

In times of war, such ethical tongue-twisters tend to give way to the pragmatism of national politics. In 1943, James Collip, one of the ‘Toronto group’ of scientists that isolated insulin, observed that: “Today, with total war upon the world, there can be no doubt that more than ever before in history this war is a contest between the brains, imagination, inventiveness and teamwork of the scientists and production workers of one group of nations pitted against those of another group.” Whereas the first three of those attributes were always common in science, teamwork, as Collip pointed out, came less naturally.

There are two ways to address the topic of science and war. The first, and the most conventional route, is to assess the impact that research has on conflict. Science in the First World War marked a turning point in tactics; no longer was a speedy and resourceful attacker likely to win. With machine guns and barbed wire at the front line, and behind them railroads for resupply, a well-dug-in defender became the favourite. (The US Civil War had demonstrated this too, but European generals were slow learners.) Technology made warfare asymmetric, and it has remained that way — the dreadful stalemate of mutually assured destruction by nuclear weapons notwithstanding.

The second route is to look at the reverse of the equation: how has conflict influenced research? What lessons are there for peacetime science in the panicked scramble of work that aims not to understand how the world works and to improve quality of life, but to ensure that it remains at all?

Nature intends to address both topics in several articles this year. And we kick off this week with a good example of each. On page 156, Sharon Weinberger reviews two books that analyse the wartime role of physics and psychology. And on page 153, David Kaiser explores how practical ways of getting US physicists to work together during the Second World War had an enduring impact on the organization and funding of science. For one thing, Kaiser writes, it turned on a “fire hose” of federal funds for research, a model that continues. The teamwork continues too, and if the stakes for winning and losing are lower now than when the original collaborations were forged, that can only be a good thing.