30 June: On this day in history

30 June 1660

English mathematician William Oughtred died at Albury in Surrey. He had invented an early form of slide rule and introduced the ‘x’ symbol for multiplication.

30 June 1859

French acrobat Charles Blondin (real name Jean-Francois Gravelet) crosses the gorge below Niagara Falls on a tightrope. He will later repeat this with variations including being blindfolded, and stopping to cook an omelette.

30 June 1934: Hitler purges the Nazi party

The dictator tightens his grip on power through a spate of ruthless killings

Ernst Röhm was asleep in his hotelin the lakeside town of Bad Wiessee when the fatal knock came. It was just after dawn on 30 June 1934, and the leaders of the Sturm Abteilung, or SA, paramilitaries had been relaxing at the Bavarian resort before their planned meeting with their party leader, Adolf Hitler. For months, tensions had been building within the Nazi hierarchy, not least between the SA and the army. Now Hitler and Röhm were going to sort all of these tensions out, although not quite in the way the latter was expecting.

When the SS men stormed in, Röhm was taken entirely by surprise. Hitler was there, too, and as Röhm gaped in horror, the Nazi leader ordered him taken away by two guards. Once the SA leadership had been rounded up, Hitler drove back to Munich. At the local party headquarters, he told a crowd that the SA had been planning a coup, the “worst treachery in world history”. It was time to root out the “undisciplined and disobedient characters and asocial or diseased elements” within their own ranks. The crowd howled their approval.

In the next three days, dozens, possibly hundreds of people were killed. The victims included not just the SA leader- ship, but old Nazi comrades who had fallen out with Hitler, senior figures in the Catholic Centre Party and, most famously, Hitler’s predecessor as Germany’s chancellor, General Kurt von Schleicher. Röhm himself was shot after refusing to commit suicide. Now Hitler’s power was unchecked. For as he boasted to the Reichstag, the Night of the Long Knives had confirmed his status as “the supreme judge of the German people”. | Written by Dominic Sandbrook

30 June 1971

The crew of the Soviet Soyuz 11 space mission, Georgi Dobrovolksy, Vladislav Volkov and Viktor Patsayev, were killed when their capsule depressurised during preparations for re-entry into the earth’s atmosphere.

Browse more On this day in history

• Previous: 29 June
• Next: 1 July