I've just checked out Henry V, Act IV, Scene III.

'This day is called the feast of St Crispian:
He that outlives this day, and comes safe home,
Will stand tip-toe when the day is named,
And rouse him at the name of Crispian'.

A quick google shows Crispian was a Roman noble and missionary c.286 AD who was tortured and beheaded.
He is indeed the patron of cobblers, leather workers, saddlers and tanners.

Further in Shakespeare's speech for Henry V:

'We few, we happy few, we band of brothers;
For he to-day that sheds his blood with me
Shall be my brother, be he ne'er so vile,
This day shall gentle his condition*'

*Henry V promised to make commoners who survived the battle members of the gentry.

I wonder if that's why Shakespeare (or Henry V) used St. Crispian for special appeal, to put heart back into the commoner English soldiers?
I've heard the Agincourt victory was largely due to the English archers.
But now I'm wondering whose great PR speech this was, Henry V or Shakespeare.

In the early C19th, France and England were on uneasy terms. JA knew her navy brothers could see battle action. Perhaps this is why she comments on 'the famous Battle of Agincourt'.