St Crispin’s Day: Why do we mark St Crispin’s Day and the Battle of Agincourt?

It continues:

Crispin Crispian shall ne’er go by,

From this day to the ending of the world,

But we in it shall be rememberèd;

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:

And gentlemen in England now a-bed

Shall think themselves accursed they were not here,

And hold their manhoods cheap whiles any speaks

That fought with us upon Saint Crispin’s day.