The service and the silence, with everyone standing under umbrellas, the flat landscape all around and a hundred years since the gunfire ceased, isn't something I'll forget, and I'm glad we made the journey. We walked away as the brass band played Abide With Me.
Afterwards we travelled to the nearby Ulster Tower, the memorial to troops from Northern Ireland. Although less than a mile down the road from Thiepval, there was almost nobody there, and we were welcomed warmly by the young Irishman serving in the shop/café. Someone had brought them a beautiful sponge cake decorated with poppies, and you could enjoy a slice in return for a 1€ donation towards blind veterans. Rude not to, eh?
In the afternoon we booked on a tour of the Wellington Tunnels, originally quarries but pressed into service in the First World War to billet troops in advance of the Battle of Arras, and then in the Second as air raid shelters.
We were given proper safety helmets made in the shape of a wartime steel helmet. As the lift descended, I looked around and saw we had been transformed into a ragtag party of miners and bantam soldiers.
The tunnels, decorated with helpful hand-written signage from both wars ('W.C.'), soldiers' drawings on the walls, and objects from the warlike to the everyday discovered during the renovations, were spookily atmospheric, especially when we came to one of the exits, dynamited before the battle for a surprise attack.
Having emerged, we explored Vauban's citadel, visited the town war memorial (which includes a Lutyens-designed monument to airmen with no known grave), then sat on the Place des Héros for a while, watching the people pass and the sun go down, before returning to the hotel.
It being Sunday night in France, we then walked 2km along a dual carriageway for dinner at a steakhouse on a retail park.
Rain was forecast for Monday morning, and we set off as late as we could. We made a brief stop at Gavrelle, where an anchor surrounded by broken brickwork commemorates the village's destruction and the Royal Naval Division's losses in the battle around it.
I was looking forward to visiting the memorial to pilot Albert Ball, situated in the field where his SE5 crashed fatally in 1917. His father bought the field in order to set up the memorial, then gave it to the French army on condition the stone was not disturbed.
Though it's in the middle of nowhere, others had been here before us to lay a wreath. I'd brought a poppy for Ball (it's on the left), which meant I spent all weekend feeling bad about the thousands of less famous dead for whom I had nothing.
Our last stop before Calais and the ferry was Fromelles, where a diversionary attack in 1916 cost several thousand soldiers, mostly Australian, their lives.
In 2009, a mass grave containing 250 bodies from the war was excavated nearby. The work of identifying them, and contacting their families, is still going on. Nine have been identified this year.
I've visited a number of military cemeteries in France and Belgium, and the impact of seeing those lines of headstones never grows less. I'm fascinated by the inscriptions, most chosen from poems or the Bible but others more personal. I'd love to know who Nettie was, and why her friendship with 204604 Private V. Clink was so special: