Denny,
I leave the discussion of the failure of this offensive to the specialists in this field!
I can only say the German sources underline the Allied Air supremacy and overwhelming strength of artillery fire against German units which suffered from a lack of ammunition and were losing already 9 observation balloons on 25th June. The latter air attack and the continued Air offensive were preventing this kind of observation in the next time. An Allied deserter reported a future Allied main attack on 29th June. Surprisingly my source (Max Schwarte) states also that some German air units were just coming from the East (!) to the Somme. So it seems now it was more an exchange of air units than an one-sided transfer to the East! I think that supports Dan-Sans evaluation of the situation.
The contemporary Allied sources add the Allied failure often to bad weather, the German sources to the fighting spirit and the better training of the German infantrists. Especially the ability to make independend decisions by themselfes (if cut-off by the enemy) and the art of improvisation was underlined in German sources. Obviously the Allied artillery did not knock-out all German artillery positions and bunkers (some survived even 24 cm-hits).
VBR
Hannes