There is something about a centenary that can bring an event vividly back to life. It's as though the passage of 100 years means it happened at precisely this point in time's cycle. The Anzacs went ashore this morning, if you will.
Centenaries of the battles and campaigns of World War I are a five-year feast of chances to relive history at a safe distance from the real thing, and so far we are getting good books to guide us through events, year by year.
Last year Sir Max Hastings' Catastrophe was with me through the opening phases from August to December when Germany was driven back from the portals of Paris and both sides dug in on the Western Front.
This year, if you still will, Britain's War Council has moved ships and invading forces to the Eastern Mediterranean at the urging of a junior member, Winston Churchill, who has a plan to expose the "soft underbelly" of the axis. This will be the story of the year and my new companion is Alan Moorehead's classic Gallipoli, reprinted for the centenary.
Thanks to him this morning I can see 1500 young Australians standing quietly in 2am darkness on the decks of three battleships in the Aegean Sea. They were to make the first assault. They were given a hot drink, hoisted backpacks, slung their rifles and went down rope ladders to landing craft.
Crammed together, they sat for two more hours under tow by the ships. Once they could see the dark outlines of land they heard the towlines drop away and saw the comforting bulk of the ships slip behind them.
Dawn was breaking when suddenly a rocket rose from the cliffs in front of them and they heard a burst of rifle fire. They sprang from the boats 50m from the beach. A few were cut down, the rest made it to the shore. The first day of the Anzac story is well known - wrong place, cliffs, heavy fire soon coming down. More landing craft coming in, the New Zealanders on the beach around 11am, scrambling for a way to press forward.
Today it began but there would be other days, like May 18 when the Turks attacked the Anzac lines. Moorehead compares that day to a hunt, "with Turkish officers driving the game on to the guns."
The Anzacs, he writes, were filled with "a wild, almost berserk excitement. In order to get a better view many of the soldiers jumped up and sat astride the parapets, and from there they blazed away at the screaming mass of Turks." The carnage went on that day for six hours. We should give it a thought on May 18.
And the day after that we could take some quiet pride in the decency of soldiers. When their commanding officers were slow to arrange a truce for the dead to be buried, ceasefires were agreed between the men in opposing trenches.
They emerged, had a smoke together, went about recovering the bodies and went back to war, but not quite as before. Until that day, Moorehead says, the Anzacs had loathed their enemy. After the May attack all real rancour died out. When gas masks were issued to Allied troops on all fronts later this year, the Anzacs declined them. "The Turks won't use gas," they said.
Australian-born Moorehead had seen enough Anzac Days when he was writing in the 1950s and he produced more than a tribute to the diggers. He follows the fortunes of all forces in the Dardanelles, giving particular praise to the New Zealanders. So does Hastings in an introduction to a centenary reprint for Aurum Press, London.
Hastings calls the New Zealanders "in both wars perhaps the finest of all Allied fighting soldiers."
They were fighting as a British dominion but in the First War they knew they were already a different breed from the campaign's distant commanders, "poet generals", as Moorehead calls them.
He found an elegant rumination on war in the diary of the Commander in Chief at Gallipoli, General Sir Ian Hamilton.
"Once in a generation," Hamilton wrote, "a mysterious wish for war passes through the people. Their instinct tells them there is no other way of progress and of escape from habits that no longer fit them.
"Whole generations of statesmen will fumble over reforms for a lifetime which are put into full blooded execution within a week of a declaration of war. There is no other way. Only by intense sufferings can the nations grow ... "
That was probably how all of humanity thought, fought and celebrated war through the centuries - until exactly 70 years ago.
At the centenaries of the Great War we ought to remember why there is unlikely to be another, and observe Hiroshima too.