What is the meaning of [Once more unto the breach, dear friends, once more]

Let us try again one more time.

‘Once more unto the breach’ – is from the ‘Cry God for Harry, England, and Saint George!’ speech of Shakespeare’s Henry V, Act III, 1598.

Once more unto the breach, dear friends, once more.The most celebrated rendition of the speech comes from Laurence Olivier’s performance in the 1944 film The Chronicle History of King Henry the Fifth with His Battell Fought at Agincourt in France, better known to the world just as Henry V.

The breach in question is the gap in the wall of the city of Harfleur, which the English army held under siege. Henry was encouraging his troops to have courage and attack the city again, even if they have to ‘close the wall with English dead’.