A brief outline of Shakespeares’ play.
The play was written around 1598 when Shakespeare was in his mid thirties. The events in the play are not always historically  accurate.

Chorus is our narrator and in a series of great speeches he guides us through the play.
At the start of the play King Henry will not go to war against France without just cause. The Archbishop of Canterbury persuades him he has that cause. War is declared and the French deliver an insulting message to the King.

The troops prepare to sail from Southampton but the King discovers two spies in his ranks. They are disgraced and executed. The English army, full of hope, set sail for France.
Back in London Sir John Falstaff is dying and his comical, rough band of  friends prepare to follow the King to France.

In France the French King prepares his defense. The Kings eldest son (the Dauphin) is scornful of the English forces. The French are confident of easy victory.
King Henry and his men first see action at the battle of Harfleur. The English are pushed back but urged on by their King : Once more into the breach dear friends! - the band of brothers eventually win out.

The next, decisive, battle will be near the town of Agincourt in Northern France. It takes place on St Crispins Day (25th October) 1415.

King Henry refuses to give up despite a small, tired, hungry and battle weary army. The French Lords laugh and joke about what will be a walk over for them.

The night before the battle of Agincourt the King wanders about his camp in disguise. He speaks to his men as if an ordinary soldier himself. 
The morning of the battle arrives. The English soon have the upper hand and the French suffer huge losses. The English and Welsh archers do most damage. Henry orders the killing of all the French prisoners. The English win but the losses and the fighting has been awful.
The marriage is arranged between Katherine of France and Henry of England. This is partly a political move to help heal the wounds that the war has made.

Into the Breach by Mark Carey