At Agincourt, the French had six thousand crossbowmen and the English five thousand longbowmen.
Research shows that both weapons fire about the same distance with the crossbow having perhaps the greater accuracy. However, for the conditions of this battle, the longbow had a decisive advantage: it could be fired many times more frequently than a crossbow. One study shows an average of 12 times a minute for the longbow compared to four times a minute for the crossbow or three to one.
To model this in AGINCOURT, the game, it was decided to add a plus one modifier to the d6 roll for a longbow to hit and to modify the crossbow hit roll by -1.
If to hit a unit must roll a five or a six, the longbow unit will hit on d6 rolls of 4, 5 and 6. The crossbow unit will hit on rolls of only 6. The longbow unit, then, will hit three times as often in the same time interval, reflecting the 3 to 1 firing frequency advantage of the longbow over the slower crossbow.