Say what you will about Shakespeare. The writer knew a thing or two about human motivation – specifically, how to get people to do something they don’t really want to do, or is contrary to their own best interests.

Rhetoric (the art of persuasion) was a much-valued skill in Tudor England, and Shakespeare would have received rigorous rhetorical training at his grammar school in Stratford-upon-Avon.

In Shakespeare’s tragedies the rhetorical arts were a high-stakes contest for controlling the masses. Was Julius Caesar murdered or was he sacrificed? The answer depends on whether you’re swayed by Antony’s or Brutus’ version of events. While in the history plays, the stakes don’t get higher – or the claims more lofty – than in the call to war.

On the muddy fields of Agincourt in Henry V, things look decidedly grim for the king’s side. The French outnumber the English five to one and their forces are ‘fresh’, unlike the wearied English. Salisbury rightly notes that these are ‘fearful odds’. King Henry has a daunting task before him: to convince his men that they should willingly enter a fight they have no real hope of surviving. Or to borrow a line from one of his soldiers, the king is expected to say something – anything – ‘to make us fight cheerfully’.

Henry’s Saint Crispin’s Day speech, which is what his pre-battle oratory has come to be called, is a masterclass in convincing others to do what they would much prefer not to – namely, march to their death.

In fact, during World War II Winston Churchill was an enthusiastic supporter of the project by Laurence Olivier, a personal friend, to adapt Henry V for the big screen. It was Churchill’s hope that Shakespeare’s play would boost the strained morale of troops fighting abroad and of Britons at home.

The uses of Henry V as wartime propaganda have been widely recognised. But there’s a tension in the Saint Crispin’s Day speech often overlooked, one which troubles a reading of the king’s address as merely soaring rhetoric to galvanize his fighters.

Henry’s speech turns upon the invocation of a pair of third-century Christian martyrs who are said to have been executed on the same date – 25 October – as the battle of Agincourt in 1415.

This day is called the feast of Crispian.
He that outlives this day and comes safe home
Will stand a-tiptoe when this day is named
And rouse him at the name of Crispian.
He that shall see this day and live old age
Will yearly on the vigil feast his neighbours,
And say, ‘Tomorrow is Saint Crispian.’
Then he will strip his sleeve and show his scars,
And say ‘These wounds I had on Crispin’s day.’

According to legend, Crispin and Crispinian (or Crispianus) were two brothers of noble birth who had converted to Christianity. They left Rome, settling in northern France to escape persecution and to propagate their faith. To support themselves and provide charity to the poor, the high-born brothers learned the trade of shoemaking.

In the end they were seized and beheaded by the Roman authorities for refusing to renounce their faith, and the martyred brothers became the patron saints of cobblers, shoemakers, and leatherworkers, their feast day celebrated on the anniversary of their deaths.

King Henry alludes to both saints when he says ‘Crispin Crispian shall ne’er go by . . . But we in it shall be remembered’. What’s interesting about Henry’s speech is the way he uses the brothers’ story to whip up his men. More precisely, it’s what Henry doesn’t do with the narrative that’s so striking.

The obvious rhetorical move would be for Henry to compare a soldier’s courage in battle to a martyr’s fortitude in facing death; or, to liken the sacrifice of his men at Agincourt to an earlier act of Christian heroism.

But Henry doesn’t do any of this. As scholars have noted, Henry invokes the brothers’ feast day only to replace it with a secular account of remembrance. In other words, he hijacks the saints’ holy day to make it about commemorating his own deeds:

Then shall our names …
Harry the King, Bedford and Exeter,
Warwick and Talbot, Salisbury and Gloucester,
Be in their flowing cups freshly remembered.

What’s also notable about Henry’s speech is that while an ordinary soldier in the king’s army might bear the scars of battle, only the names of noble men will be ‘familiar … as household words’.

History has borne out the truth of Henry’s oratory. Today, Saint Crispin’s Day is more remembered for its association with Henry V than for the lives of two martyred saints. It can thus be said that after Shakespeare’s play, Saint Crispin’s Day more properly pays tribute to England’s former king rather than its shoemakers.