It was the day that up to a fifth of Dundee’s population died.

Some 362 years ago this month, the city was witness to one of the worst massacres ever committed on Scottish soil.

We think of Dundee as leaning slightly to the left the strong union heritage, the city that kicked Winston Churchill out, that sort of thing.

But in the time of the Civil War of 1642-1651 which saw republican Oliver Cromwell destroy the English Crown and execute Charles I, Dundee was a royalist stronghold.

Behind its stout stone walls it was one of the safest towns in the entire country even Edinburgh kept its gold reserves in Dundee, as did nobles from as far away as the borders.

Cromwell wanted royalist power extinguished in Scotland too so he unleashed General George Monck.

Devon-born Monck was by then 43 years old, a soldier all his days, and if there was something he knew well it was to how to handle a campaign.

He stormed into Scotland and arrived at Dundee’s gates near the end of August 1651 with his army of 7,000 seasoned Puritan troops and supporting artillery.

Dundee was not intimidated: they had their militia, they had their walls. But, unfortunately, they also had lots to drink. Indeed, intelligence gleaned from spies reported that the town’s soldiers were “usually drunk by lunchtime”.

On September 1, the day of the assault, three hours of thundering cannon fire smashed the northern wall as the city cowered.

Breaching the walls was only half the battle, of course, and Monck promised his troops that they could loot and pillage “without licence” if they took the town he was effectively telling them they could do whatever they wanted. With sword, pistol and pike the Puritans poured into the shattered wall and the city was taken in just 30 minutes.

Governor of Dundee Robert Lumsden and a handful of his troops fell back into the Old Steeple church which stands at the heart of the city centre to this day and made a desperate last stand.

Across this prosperous and well-ordered city Monck’s troops smashed into homes robbing, killing and raping. The plunder was exceptional and the murder without equal in Scotland’s history. It has been stated that the massacre only ceased when Monck himself witnessed a terrified infant trying to cuddle against his slaughtered mother and ordered his soldiers to stop.

Meanwhile, Lumsden’s embattled party only surrendered when they were promised “honourable terms”.

They laid down their arms, walked out and were murdered on the spot Lumsden’s head was displayed on a spike for all to see.

Conservative estimates for those killed are around 1,000, but some accounts state 2,000 people captured members of the garrison, innocent men, women and even children died in the carnage. Monck’s forces lost 20 killed and a similar number injured.

One of Monck’s officers later stated: “The townspeople were most obstinate, being confident of their own works and strength. But they have now most suffered for it, and paid dearly for their contempt.”

Dundee’s famed wall was torn down, the dead were buried and the city rebuilt.

As for Monck, he carefully kept his cards close to his chest and when Cromwell died, he quietly moved back to the royalist side and served Charles II. He died at the age of 62 and is buried in Westminster Abbey.

And to this very day, building work in Dundee’s city centre is likely to bring up the bones of those cut down in 1651.