What constrained Haig's choices on the Somme

The Somme is explained through the need to draw German attention away from Verdun. Haig wanted scope for manoeuvre but also had to secure transport, fodder and suitable ammunition. His request for more high-explosive shells was not fully met, with shrapnel supplied instead. The campaign did divert German resources, while failing to deliver the intended breakthrough and imposing severe losses. The large divisional totals discussed include formations rotated through the battle, rather than all occupying the front simultaneously.