On the 4th August 1914, Britain declared war on Germany and the First World War began in earnest. It drew in people from every continent, killing millions and bringing down empires. But did we learn our lesson?
Last week, I flew back from London across the channel and the Belgium coast to my home in Germany. High up in the sky, I looked down on a calm Europe, the patchwork of fields twinkling in the sun.
I then turned to talk to my German husband. We looked together at pictures of a new installation at the Tower of London to mark the centenary of the outbreak of war and, as always, the poppies brought a lump to my throat, remembering the bloodshed, death and destruction that they symbolize.
The striking red ceramic poppies flowing across the lawns on the banks of the river Thames are a poignant reminder that the world really was a very different place for our great grandparents. My marriage would never have come into being for a start, or if it had, it would have been brutally ripped apart.
Our great grandfathers fought on opposing sides in the so called Great War. Facing unemployment in the early part of the twentieth century, my great grandfather joined the Royal Marines and was sent to fight at Gallipoli – he thankfully returned. He kept a diary which my uncle has now, his experiences pawed over by our family for clues to what life was like for him then.
My husband Maik's great grandfather was a railway-man and so perhaps, luckily for him, he was in charge of building the rails that transported the big guns for the artillery to the front in France which he then operated at Verdun. The big guns were positioned behind the front lines and although they, too, suffered casualties, Maik's great grandfather managed to return home as well.
One Christmas I sat with Werner, Maik's dad, as he got out his memory box and showed me photos and postcards that Maik's great granddad sent home from Verdun. We looked at his conscription book and at postcards where he talked about what he had seen in France outside of the battle. We still have a knife which he took from a farmhouse in France as the army retreated, so desperate were they for something to eat and for something to cut the bread and cheese that they had purloined.
By all accounts, neither man spoke much about the horrors they presumably saw in battle when they returned home. But their diaries, letters and mementoes have been kept by our families and help to underline for us the human element to the war which redrew Europe.
We've been told that both these great grandfathers were gentle, kind people - sent to fight a war which perhaps neither of them really understood, in countries that they would never have even dreamt of seeing had it not been for the power politics of their leaders.
All this year, I've been avidly consuming the TV dramas, the recreations, the poetry and the literature relating to the First World War and its anniversary. And every time I read, watch or listen, I cry.
It doesn't matter who died or whose side they were on. What is sad is the senseless waste of life: that millions of ordinary people, like us, got swept up into that horror and were forced to lay down their lives in the mud and the earth.
What did we learn?
Of course, 100 years on, Europe IS a very different place. That I can fly over a calm Belgium and live in Germany is testament to that. But as I watch modern horrors on the television unfolding in the Middle East, Libya and within Europe, in Ukraine, I wonder if we've really learnt as much as we think from the sadness, mess and confusion that was the reality for our great grandfathers, just 100 years ago.
Some days though, on watching the news headlines, countries unraveling and millions on the march, I wonder if the world is heading for a Third World War, much more horrendous than even we can imagine from our own history.