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Jus Post Bellum – Ending War and Ending Wars Well

By David Whetham, KCL, EuroISME Board Member

At the start of the current conflict, I wrote a short piece on the crime of aggression and the ethics of starting wars, drawing on the work of Michael Walzer. Amongst the many editorials in the press today commemorating the first anniversary of the Russian invasion of Ukraine in February 2022 (and remembering that this followed the earlier annexation of Ukrainian territory), I thought it might be useful to return to Walzer and his thoughts on how wars end. The ethics of ending conflict goes under the Latin title jus post bellum, and the whole topic touched on below is explored in more depth by Cian O’Driscoll, Andrew Hom, Kurt Mills and Phillips O’Brien in a free online course at the Centre for Military Ethics.

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War Aims

What soldiers fight and kill and suffer and die for must matter for their sacrifice to be worthwhile. This is expressed by the British WWI poet, Wilfred Owen, in his poem, Smile, Smile, Smile. ‘Peace’, he writes, ‘would do wrong to our undying dead; The sons we offered might regret they died; If we got nothing lasting in their stead.’ His point, and it is one that we can all share, is that it is important to say of those who fight and kill and die in war that they do not do in vain. There must be some purpose, some higher end that is served, by their actions, otherwise blood will have been spilled to no avail. If a war is to be considered just, it is vital that it achieves something worthwhile, something to validate and justify the sacrifices made on its behalf. So what might this entail? What, in other words, should we consider as a worthy goal for which soldiers may justifiably fight and kill and die? What should we regard as a legitimate war aim? There is a spectrum of possible answers to that question:

A War To End to All Wars

We can label the first answer to this question the Wilsonian solution, after Woodrow Wilson, the former US president. It resides all the way to one end of the spectrum. If war is a terrible thing, as some people say, it is presumably only justifiable to wage it for the most elevated of goals. This appears to have been President Wilson’s view. He was initially hesitant to involve the US in the First World War, a war that he equated with European great power rivalry and imperialism. It was only when he could convince himself, and perhaps others, that civilisation itself was at stake that he licensed US intervention in the war. In light of this, he described American war aims in the most grandiose terms. This would be, he said, a “war to end all wars.” While we can all presumably understand the sentiment that if war is to be waged at all, it should only be for the highest stakes, this position is deeply problematic. It not only sets goals that can never reasonably be expected to be achieved, thus condemning soldiers to fight for a cause that can never be realised, it also risks exacerbating a conflict. It does so by escalates the conflict, painting one’s own side as the defenders of civilisation, and the enemy as villainous. Where this is the case, restraint becomes harder to achieve, and the likelihood of atrocities increases.

Mowing the Lawn

At the very opposite end of the spectrum is what we might call the remedial solution. It is best introduced by reference to the war aims stated by the Israeli Defence Force,

or IDF, in respect of its recent armed incursions into Gaza. These missions were not undertaken, they told us, to achieve some exalted war aim, such as the end to all war, but instead to promote only very limited of objectives. The language used by IDF spokespersons to describe these objectives was ‘Mowing the lawn.’ What this was intended to signify was that the IDF was undertaking military action against Hamas forces in Gaza not to eradicate the threat that they posed, for this would be impossible, but merely to minimise it, to curb its growth, to keep it under control. The language is purposefully modest. It is intended to convey to the Israeli public and indeed to the wider world that the use of military means will not destroy Hamas altogether, but will only reduce its ability to threaten Israel. Moreover, any such reduction will only ever be temporary, and will require constant renewal, that is to say, repeat interventions. What is one to make of this? On the one hand, this way of thinking about war is honest and realistic, and avoids the fallacy of which the Wilsonian solution is culpable. On the other hand, it asks soldiers to risk their lives and spill blood in the service of a very provisional and basic war aim. As such, it must raise serious concerns.

Unconditional Surrender

Having introduced the extreme ends of the spectrum, we might zero in on a position that lies somewhere between them, albeit closer to the Wilsonian end. This is the policy of unconditional surrender. It is closely associated with the Allied war aims in WWII, when Prime Minister Winston Churchill demanded unconditional surrender from Nazi Germany. Churchill was very clear to the UK parliament that this did not mean that his government was seeking the outright destruction of Germany, or that it felt entitled to do anything it so wished to Germany. Rather, it signified that the UK and its allies would not bind its war aims in any way to the Nazi government or to any Nazi conditions. This in effect involved two commitments. The first was that the Allies would not negotiate with Nazi leaders, and would have no dealings with them whatsoever except to demand their capitulation. The second was that no German government would be recognized as legitimate until it had unconditionally surrendered, acquiesced with Allied occupation, and consented to the Allies’ right to institute regime change in Germany. This demand amounted then, essentially, to a call for the conquest and political reconstruction, that is, regime change, of the enemy state. Is this an appropriate aim for war? Or is it going too far?

Specialists in the field argue that it is the outer limit of what is acceptable. They argue that it is only against an enemy as wicked, as craven, as Nazi Germany could such extensive war aims ever appear legitimate. With a government as hostile and as deeply entrenched as the Nazi regime, there seemed no other way to defeat it than to comprehensively destroy it. In a more typical case, such intrusive, wholesale measures would not be justified. This is because they risk punishing the society at large for the crimes of its government by suspending its capacity for self-determination.

Limited War Aims

Having discussed illustrative cases at either end of the spectrum, it may be helpful to consider one case that perhaps falls in the centre. This is the case of the Gulf War, 1991, when US and UK forces led a UN-authorised mission to expel Iraq from Kuwait

and protect Saudi Arabia. Iraq’s presence in Kuwait was, of course, the result of an act of aggression, wherein Iraqi forces moved across the border and seized Kuwaiti territory in a bid to annex it. Once all diplomatic avenues had been exhausted and the UN authorised a military response, the Allies launched a massive attack on the Iraqi army in Kuwait. Having first softened it up with an extended period of aerial bombardment, a ground invasion was set in motion that, ultimately, would defeat the Iraqi Army in less than 100 hours, causing it to beat a hasty retreat from Kuwait, back to Iraq. The question that arises at this point is, How far should the Allies extend their war effort? Should they seek the conclusive destruction of the Iraqi military apparatus in the field? Should they perhaps even aim to push on and occupy Iraqi territory? Going even further, should they aim to remove Saddam Hussein from power, and install a more amenable partner in his place?

As we know, President George H. W. Bush made the decision to call a halt to the war before these objectives were in sight. He deemed that, once Iraqi troops were already on the run, any further attacks against them would be extraneous, and therefore morally problematic. Consistent with this, and with his understanding that the war was authorised by the UN on the basis that it was directed toward the defence of Kuwait, President Bush opted against the conquest of Iraq. The argument here was that to extend the war to Iraqi territory would exceed the war’s basis in law, and thus, after a fashion, constitute an act of aggression in its own right. Is this, then, a perfect case study for how to end a war? Or did President Bush, by stopping the war so soon, simply sow the seeds for the next Iraq war, which could of course take place in 2003?


In conclusion, there are no easy answers to any of these questions. However, it is still important that we think through them. They speak to the matter of what can be achieved by war, and challenge us to think about what counts as a good enough reason to ask a soldier to fight and kill and die in the name of his or her community.

To explore the subject further, have a look at Jus Post Bellum: Ending War and Ending Wars Well.

Credits: Foto von Faris Mohammed auf Unsplash [cropped]

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