"There's very little will to stop these wars - from Yemen to Syria"

• BBC Radio 4 Today programme slips up over Jeremy Hunt's name AGAIN
• Sign up for the free RadioTimes.com newsletter here

Her acclaimed book, The War That Ended Peace, helped us understand the First World War, and she’s now exploring the tangled history of war and society through the centuries in the BBC’s Reith Lectures. From the ancient Roman Empire, to the French Revolution, to future wars fought by robots, what is it about conflict that horrifies, fascinates and attracts us?

Her first lecture in the series – broadcast on Tuesday on Radio 4 – calls on us to consider if war “is part of what it is to be human”. What an uncomfortable truth. “Wouldn’t we want to consider war as an aberration,” I ask her. “Well, if it’s an aberration, it’s an aberration that has happened an awful lot of times!” she says.

I notice that each title of her five lectures – which take her to places as different and distant as Ottawa and Beirut, as well as to York and Belfast – points to a paradox. To begin with, there’s war and humanity, as well as warriors both feared and loved, and our efforts to manage what is described as unmanageable war.

As a journalist who often writes those proverbial first drafts of history in the heat and horrors of war, I have more than a passing interest in the reflections of a historian who divides her teaching time between Oxford University and the University of Toronto.

We meet in a fitting venue. The Radio Theatre behind Broadcasting House in London, at the heart of the BBC, was built underground to allow the BBC to broadcast continuously during the Second World War – even when the building was hit by bombs on 15 October 1940.

MacMillan begins her series with an anecdote about that fateful explosion, which took the lives of four men and three women. The newsreader for the BBC’s nine o’clock news paused briefly, then just kept going.

Almost 78 years on, journalists are even more of a target in contemporary conflicts. Even our new tools of social media have become weaponised as opposing sides try to seize the high ground in the world’s brutal battle.

But there is another troubling paradox. Our world has never been so educated, so wealthy, so connected by technology and ease of travel. Not only can we know more than ever before about distant wars, we also have an unparalleled architecture to prevent and punish abuses: war crimes tribunals; global networks of human rights organisations; volumes of international humanitarian law. So why do conflicts still unfold with shocking impunity?

“There may be a demographic explanation that’s part of this,” says McMillan. “In some parts of the world – in North Africa, the Middle East, parts of Asia – you have an awful lot of young men (and so far, it’s been young men who have done the bulk of the fighting in history) and they’ve got no future, there aren’t jobs for them.

“What are they going to do? A man with a gun has a certain authority – you can push others around. And so, the temptation to go into that way of life is enormous. But you’re right, there is a paradox. We have all sorts of rules, but many wars. I’m worried that the great powers are losing interest. The United States doesn’t want to be the world’s policeman, and that’s not just down to President Trump. There are others in the United States saying, ‘We’ve done it long enough.’ Well, if the great powers don’t do this, who’s going to do it?”

The results of this reluctance are visible on the front line. In Syria, medieval sieges are now weapons of choice, mainly for the government but also rebel groups. Entire towns are squeezed to surrender or starve. In the Democratic Republic of Congo, the systematic rape of women is a weapon of war. Everyone says that they don’t target civilians. But everywhere, there’s horrendous suffering. Why?

“It was striking, before the Second World War, that words like ‘insects’ and ‘vermin’ were used to talk about the other side,” says MacMillan. “When you start talking like this, they’re no longer human.”

Eighty years on, there’s a new language. “These people are terrorists,” says MacMillan. “They’re Isis, or they’re radicals, so they’re not really like us, and we have every right to kill them.”

War marches on by dehumanising humans. And even as armed confrontations between states occur less, civil wars go on and on. So much so, we’ve come to call them “forever wars”.

“They’re very difficult to stop,” reflects MacMillan. “Outside powers meddle in them for their own purposes, but I think there’s very little will to come in and actually stop these wars.” From Syria to Yemen to Afghanistan, there are tangled wars within wars.

How do we start to untangle such conflicts? It may be tempting to think we could begin by removing (or replacing) the war-makers “Our newsreaders should just start saying, ‘Here are the terrible things men are doing today,” quipped a former Reith lecturer at a dinner I attended to mark what would have been the birthday of Millicent Fawcett, the suffragist who played a key role in winning women the right to vote.

Would it make any difference if more women were leading war cabinets and commanding the forces? “There was that argument that if we had more women in positions of authority, the world would be a nicer place,” says MacMillan. “And then we got Golda Meir, Margaret Thatcher, Sirimavo Bandaranaike, Indira Gandhi. When women become acclimatised to war, they can become every bit as ruthless as men.”

But then she pauses to add a careful caveat. “I’m not sure I’m going to say that women and men are exactly the same. I think we may have different ways of approaching things, different sensitivities, and women are often better than men at picking up emotional cues.”

From the sweep of history, there’s wisdom and a warning: “If we don’t take responsibility for each other, it seems to me the future is going to be even bleaker.” The unmentionable could become the unthinkable.

The Reith Lectures airs on Tuesday 26th June on BBC Radio 4