Cromwell is impatient to take Clonmel as…

Cromwell is impatient to take Clonmel as he had been summoned back to England by the English Parliament to deal with a Royalist uprising there.

As a result he tries to take the town immediately by assault, rather than opt for a lengthy siege.

Cromwell’s artillery, positioned on a hill near present-day Melview, batters a breach in the town walls.

It is intended that his infantry will storm this breech and then open the nearby North town gate to allow access to Cromwell and the Parliamentarian cavalry.

However, O’Neill puts all able bodied townspeople to work building a coupure inside the breach lined with artillery, muskets and pikemen.

The coupure is v-shaped, starting at the mouth of the breach and narrowing until it ends about 50 meters inside the town.

At the end of the breach, O'Neill positions two cannon, loaded with chain-shot.

The area behind the breach becomes, in military terms, a "killing field".

The Parliamentarian infantry which assaults the breach on May 17 is repeatedly cut down by the concentrated musket and cannon fire until the soldiers finally refuse to make any further attacks on what is a death trap.

Cromwell now appeals to his elite cavalry, the Ironsides, to make a fresh assault on foot.

They assault the breach for three hours, taking heavy casualties but failing to break into the town.

Eventually, as night falls, Cromwell calls off the assault.

O’Neill’s men are out of ammunition, however, and slip away under cover of darkness—making their way to Waterford.

Cromwell negotiates a surrender with the town’s mayor, John White, believing that Clonmel is still heavily defended.

The surrender terms stipulate that the lives and property of the townspeople will be respected.

Cromwell, although angry at the deception, does not allow his soldiers to abuse the terms of the surrender when he finds that the garrison is gone and the town defenseless. (His admirers cite this as an example of his integrity while his critics contrast it with the massacre he had ordered at Drogheda the previous year.)

The New Model Army has lost at least fifteen hundred men killed at Clonmel, and possibly as many as twenty-five hundred, with hundreds more wounded, its largest ever loss in a single day.