Countless protest signs have informed us over the years that “war is not the answer.”

We hear this message, with varying levels of sophistication and differing underlying worldviews, from institutions and people ranging from Code Pink to Pope Leo. 

“War does not solve problems,” the pontiff said in an Angelus address last year.

“On the contrary, it amplifies them and causes deep wounds in the history of peoples — wounds that take generations to heal.”

Now, there are many things that can be said about the tragedy of warfare without crediting the blatantly ahistorical cliche that it is never the answer.

Or that it doesn’t solve disputed questions, often with a terrible finality. 

Warfare can determine international boundaries and the nature of governments.

It can decide who will rule and who will not.

The relative power of states, the extent of religious faiths, and the status of a culture can depend on it. 

Wars might be pointless, or fought for prestige, revenge or territorial aggrandizement.

That’s all true, but doesn’t change the fact that military conflict is, at times, necessary and highly consequential; it can achieve beneficent ends, as well as awful ones. 

It mattered for the spread of Christianity, for instance, that Constantine, who would become the first Christian emperor of Rome, won the Battle of Milvian Bridge in 312.

Later, Christendom benefited from Ferdinand and Isabella taking back Granada from its Muslim rulers in 1492, and from the Holy Roman Emperor defeating the Ottoman besiegers of Vienna in 1683. 

Certainly, it would have been better if all this could have been amiably worked out among the relevant parties, but that’s not how the world usually works. 

In the early 19th century, Europe had a Napoleon problem — a world-historical military genius determined to bend the continent to his will through force of arms.

After serial failures, the Allies finally solved this problem in the War of the Seventh Coalition.

The ensuing diplomatic settlement at the Congress of Vienna forged a peace that lasted nearly a century, but wouldn’t have been possible without victory at Waterloo. 

In the early 20th century, Europe had a Hitler problem — a fanatical, race-obsessed militarist who wanted his Third Reich to dominate Europe.

This problem, too, was solved by force and led to a lasting peace, although a very tense one during the Cold War.

If it’s true that war should usually be the last resort, the Allies would have been better off if it had been the first resort against Hitler, checking him when he was relatively weak. 

More parochially, the United States wouldn’t be what it is today absent two existential wars.

When the colonies began agitating for independence, the British weren’t simply going to cede what they considered sovereign territories, especially given their economic and strategic value.

The American cause — and all the good that has flowed from it — depended on prevailing in a grinding eight-year war.

About 100 years later, it all could have collapsed had the United States not prevailed in the Civil War, an appallingly bloody conflict that extinguished American slavery and preserved the foundation for the nation’s gathering greatness.

None of this is a warrant for heedless warmongering, or a reason to dismiss, say, the sheer cynical brutishness of the Roman destruction of Carthage in the Third Punic war, or the horrors of Passchendaele.

That war is terrible, however, doesn’t mean that it’s ineffective. 

In our times, Russian invaded Ukraine in 2022 in the erroneous but not crazy belief that a sharp, decisive military campaign would topple the Western-oriented government in Kyiv and force the creation of a regime more to the Kremlin’s liking.

This was a war that never should have been launched, yet Ukraine had no alternative but to fight it.

If Kyiv wants to protect its sovereign territory and eventually get a tolerable diplomatic outcome, war is the answer — as, sadly, it has been so often throughout human history. 

X: @RichLowry