One way of determining this is to look at the percentage of the body
covered in effective plate. In the early HYW this was considerably
less than at the end. Agincourt (1415) is the midway point in plate
armor development; still more like Crecy and Poitiers than Formigny
(1450). If the archer in question is at a range where he just doesn't
miss a target like a man-at-arms on foot coming straight at him, then
the base chance for an effective hit becomes the percentage of plate
covered area. With even cap-a-pie steel plate, like that commonly worn
at the end of the HYW, this is never going to be less than c. 6%; and
that would be with full face coverage. As the man-at-arms moves he
exposes the joints at his elbows and shoulders. The breaths and eye
slits are thin. From the flanks his vulnerability goes up double that;
and from the rear quarters his vulnerability is as high as c. 15%: any
clothyard shaft striking into the thin edges of the plate, sides of
the helmet, or hitting where the plate does not cover (butt, upper
rear thighs, backs of knees) are going to take the arrow without
turning it or absorbing much of the impact.
Men in deep, linear formation advancing into an AIMED arrow storm at
pointblank range (inside c. 70 yards) are especially vulnerable to
archery because they can't dodge or move out of formation; and the
archers in "herce" formation (projecting forward to take the enemy in
the flanks) are going to get some very effective shots in where the
plate is thinnest.
The estimated number of arrows impacting into the front rank of the
French during the last c. 70 yards of their advance at Agincourt was
c. 1,500 arrows into c. 500 men-at-arms every 5 seconds (12 rapidly
aimed shots per minute was a standard rate of "fire" for English
archers); and it took the French over a minute to close the last c. 70
yards. That is over 18,000 arrows into c. 500 front rank targets, or
c. 40 arrows received by each man-at-arms: even at the lowest possible
exposed area of c. 6% that is still over two arrows per man-at-arms
getting past the plate. Simple odds tells us that probably every
French man-at-arms in the front one or two ranks had been wounded by
arrows by the time they came to hand strokes with the English men-at-
arms. Wounds, from moderate to fatal, exhaustion from c. 300 yards of
slogging toward the English through mud in c. 60 lbs of armor, and
finally having to fight hand-to-hand against a fresh enemy: it's no
wonder the French van lost their fight! And most of the reason was the
overwhelming number of arrows used against them....
Doug