17 maart

The philosopher emperor spent years on the Danube frontier, writing notes to himself in Greek that we call the Meditations. He died on campaign and left the empire to his son Commodus.

Two centuries of relative peace inside the frontiers, kept by a standing army on the borders. Romans called the Mediterranean mare nostrum, our sea.

His patron died of tuberculosis at the Badia of Fiesole on 17 March 1515 by the Florentine count, which is 1516 by modern count, and Leonardo lost his place in Rome. Within the year he accepted the French king’s invitation.

Babur beat the Rajput confederacy of Rana Sanga of Mewar. Before the battle he swore off wine and poured his drinking vessels out on the ground to rally his frightened army.

Henry Knox had hauled the guns of Fort Ticonderoga 300 miles on sledges. Mounted overnight on Dorchester Heights, they made the harbour untenable. General Howe sailed for Halifax, taking about 1,100 Loyalists with him.

Within days some 15,000 militia from across New England had penned the British army inside Boston.

George McClellan shipped more than 100,000 men to Fort Monroe and crept up the peninsula towards Richmond. He got within a few miles of the city and was driven off.

Three camps built only to kill, in occupied Poland, with the Jews of the Generalgouvernement as their target. By the United States Holocaust Memorial Museum’s figures, about 435,000 people were murdered at Bełżec, at least 167,000 at Sobibór and about 925,000 at Treblinka.

Disguised as a soldier, the 23-year-old left the Norbulingka palace by night and reached India two weeks later. From exile in Dharamsala he and the lamas who followed took Tibetan Buddhism to the rest of the world.

After the Conservative Party won a by-election, de Klerk asked white voters whether he should go on with negotiations towards a new constitution. On a turnout of about 85 per cent, 68.7 per cent said yes. It was the last vote in which only whites took part.

On Monday rumours spread that Bear was short of cash. Hedge funds pulled their money and lenders refused to roll over its loans; its cash fell from about 18 billion dollars to 2 billion in four days. By the next Monday it had been sold.

The Observer and The New York Times reported that a personality-quiz app had harvested data on its users’ Facebook friends for a political consultancy that worked for Trump’s 2016 campaign. Facebook later put the number of people affected at up to 87 million.