I’m no military strategist, but I did play a heck of a lot of Myth and I can tell you that that is an absolutely destructive position the English have there.
I remember hearing how the English use of the longbow helped to grant them victory over superior numbers and the Wikipedia entry pretty much bears that out. Standing on the high ground with their backs to the trees and protected by spikes, the English archers rained arrows down on the French cavalry, mostly killing their horses which were only armored on the head, and forcing the riders to then slog through the mud the rest of the way in their armor on foot. When they finally reached the line they were exhausted, and the unarmored English who could move more easily in the mud made short work of them.
There’s really nothing glamorous about medieval warfare — the only ones who ever really won were the nobility — but the English were outnumbered 6 to 1 at Agincourt and everyone likes to root for the underdog.