Yes and no.
As I think was mentioned elsewhere the English longbowmen combined with (as you mention) the difficult terrain significantly hampered the French charge/advance, the French were weakened enough for English troops (including the archers) to wade in and massacre the disorientated French knights - the common misconception is that the massed archer fire at Agincourt caused massive casualties, they did cause casualties but it was the disruption of the archer fire and muddy ground that left the French vulnerable and therefore gave the English an advantage in the melee. It's just the sort of situation which explains the evolution of thin stabbing daggers in medieval warfare, walking around the battlefield finding crippled knights and stabbing through their visors and joints in the armour.