The feast day of Saints Crispin and Crispinian is October 25

Saint Crispin's Day has become famous as the anniversary of the Battle of Agincourt in 1415, when a small band of Englishmen and Welshmen defeated a technologically and numerically superior French army. Agincourt became a symbol of courage in the face of danger, and was so popular that William Shakespeare put an inspiring speech into the mouth of King Henry V, which still gives courage:

What's he that wishes so?
My cousin Westmorland. No, my fair cousin:
If we are marked to die, we are enow
To do our country loss; and if to live,
The fewer men, the greater share of honour.
God's will, I pray thee, wish not one man more.
By Jove, I am not covetous for gold,
Nor care I who doth feed upon my cost;
It ernes me not if men my garments wear;
Such outward things dwell not in my desires:
But if it be a sin to covet honour,
I am the most offending soul alive.
No, faith, my coz, wish not a man from England:
God's peace, I would not lose so great an honour
As one man more, methinks, would share from me
For the best hope I have. O, do not wish one more.
Rather proclaim it presently through my host,
That he which hath no stomach to this fight,
Let him depart. His passport shall be made
And crowns for convoy put into his purse:
We would not die in that man's company
That fears his fellowship to die with us.