Every nation that went to war in 1914 claimed, and probably believed, that they had been forced into it by the wickedness of others. It started on June 28 with the assassination of Archduke Franz Ferdinand, who was not a hawk, but the Austro-Hungarian hawks used his murder to justify the war they had always wanted. (9/11 comes to mind).

Influential Europeans had been talking for years about the possibility of war, but expected any war to be a short one.

Yet Europe had been (mainly) at peace for 100 years. Margaret MacMillan, in her magisterial study The War That Ended Peace (Profile, £25), describes a continent which was steadily growing more prosperous and civilised, but was not democratic.

The Tsar, Emperor and Kaiser had far too much power; their ministers and ambassadors were usually aristocrats. No women had the vote, and not all men.

The great powers distrusted each other and scrambled for colonies; there was no conception of a common European home or a United Nations.

“All over Europe,” says the caption to a photograph of Balkan Boy Scouts, “civilians were urged to emulate the military and demonstrate such qualities as discipline, sacrifice and patriotism.”

Part of the problem was that statesmen were afraid of appearing “weak and unmanly”. Yet there were several moments when peace seemed possible.

Rulers and diplomats on both sides genuinely tried to avoid it, but did not try quite hard enough.

It is also fascinating to hear about the lesser-known people who worked for peace before 1914 — Jean Jaures, Norman Angell and Bertha von Suttner Gordon Martel does not disagree with any of this. His book, The Month that Changed the World: July 1914 (OUP, £22.99), focuses on the tense weeks before August 4 and reprints several documents from the time, including the ultimatum to Serbia.

His epilogue, ‘Making Sense of the Madness’, discusses the arguments which have raged ever since over who was to blame. “People prefer simple explanations,” he concludes, but believes that it was a “terrible, avoidable tragedy”.

There have been and will be many other books, but these two are especially valuable. It is shocking that some people are still using the language of 1914 and arguing that ‘we’ had no choice but to sacrifice a generation of British young men. As MacMillan sums up: “There are always choices.”