Two hundred and fifty years ago, on Thursday 19 April 1770, James Cook – perhaps Britain’s greatest navigator – sighted the south-east coast of Australia while commanding HMS Endeavour. It was “rather low, and not very hilly, the face of the country green and woody”. On 29 April, he anchored in a “capacious, safe and commodious bay”, watched by Aboriginal men, women and children of the Gweagal clan. Hoping to make contact with them, he decided to go ashore, but as the ships’ boats approached through the surf, all vanished except for two men “who seem’d resolved to oppose our landing”. To placate them, Cook threw beads and nails. When that failed, he fired a few musket shots to frighten them off, and finally stepped onto the wet sand. However,…