September 3, 1941 — Zyklon B is first used at Auschwitz

One of the deadliest chemicals ever invented, Zyklon B is a derivative of Prussic acid. It was invented in 1922 by a small team of German chemists led by Nobel Prize winning chemist Fritz Haber, whose previous creations included mustard gas and other chemicals of warfare used in World War One.

In 1941, the gas was first deployed in three death camps: Auschwitz-Birkenau, and Majdanek, and Sachsenhausen. Its first large scale use was one September 3, when 600 Russian POWs, 250 Polish POWs and 10 criminals were killed at Auschwitz-Birkenau. Some of the victims survived more than 24 hours of exposure to the gas – when this was discovered, additional quantities of it were pumped into the killing chambers. By the time the war ended, an estimated 1.2 million people were killed with Zyklon B, most of whom (960,000) were Jews.

September 3, 1658 — Oliver Cromwell dies

Hated by the Irish for his invasion the previous decade, Oliver Cromwell’s manner of death must have given them some satisfaction. He died from a malarial fever contracted during the invasion (and complicated by what appears to have been kidney stones).

Cromwell had come far and achieved much in his 59 years, but little that he had built long-survived him. His son Richard, who succeeded him as Lord Protector, resigned from that role due to a lack of political support less than a year later, and King Charles II was invited back to England to reinstate the monarchy the year after that.

In 1661, on the anniversary of King Charles I’s execution, Cromwell’s corpse was exhumed, and a symbolic posthumous beheading was carried out. His severed head would be a collector’s item for some years thereafter, before being reburied in 1960.

September 3, 1651 — Cromwell’s forces triumph at Worcester

The final encounter of the English Civil War was a bruising and thorough defeat for King Charles the First and his allies. Although between them, the Royalist forces and their Scottish allies numbered about 16,000, Cromwell’s Parliamentarians had mustered nearly twice as many soldiers, and with such a massive numerical superiority, the outcome was never truly in doubt.

Cromwell took his time in the disposition of his forces, cutting off the King’s escape while wearing down his army. In a battle that lasted only a single day, the Parliamentarians surrounded the Royalists, driving them back within the walls of the city of Worcester, and capturing it shortly after nightfall. Few if any of the Royalists escaped, most being captured at the battle’s end or later that night, but the truly stunning result were the casualty lists: Cromwell lost only 200 of his 31,000, while 3000 Royalists were slain and more than 10,000 captured. The English Civil War was over, and Charles I would not long outlive it, although he did escape for a time.