ursus americanus wrote:
Canadian site at Vimy Ridge is a real eye opener and an opportunity to go down into the tunnels
Agreed - Vimy Ridge is definitely worth a visit, with the preserved trenches and access / fighting tunnels, and large areas of woodland still roped off due to unexploded ordnance. What I found particularly eye-opening were the tightly strained buttons on the shirts of the very grown-up Canadian girl scouts who act as guides at the site.
The memorial at Thiepval is incredibly moving - a huge structure, designed by Lutyens, the columns of which are covered with the names of 72,000 who died on the Somme and have no known grave.
If you are heading northeast to the WWI sites, the rather older battlefield of Agincourt is another must-see. It's about 45km NE of Abbeville / 35km E of Etaples - look for A
zincourt on the map. Despite the trouncing they received there, the Frenchies have established a very good museum / visitor centre.