Travel

I have the idea of trying to [approximately] walk the route of Henry V after the siege of Harfleur to Agincourt and Calais.[Oct 25 2015 will be 600 th anniversary of the battle] A rough calculation shows me its a b' long way, about 340 miles. So I think I will have to try and explore this in 2 stages.

Stage 1 is to link up from Harfleur to the GR21 'the Cote Alabatre' to the mouth of the Somme and then to follow the towpath down the Somme to Amiens and then Corbie.
I have researched this a bit and have info on the GR21 and Editions Du Breil guide to the Somme waterway.
Has anybody any advice about the GR21 and the Somme towpath?

Stage 2 from Corbie to Voyennes to Peronne and across the 1st world war battlefields to Agincourt and on will need a lot more investigation.

There is a IGN map (903) covering the whole of France which shows GRs and GRPs which may be of use. The Map Shop at Upton on Severn will certainly have a copy for sale.

Many thanks John and stiltwalker for your interest, I will buy the IGN map. I have looked at the France on foot website but there is not much to help me on this route.