After Dunkirk fell, invasion of Britain seemed imminent.
A concerted effort grew to remove children from those cities that were targets of German bombing raids. The government encouraged parents to evacuate their children, wherever possible, to overseas countries.
Many children were evacuated to other Commonwealth countries, primarily Canada. These Atlantic voyages through U-boat "wolf packs" were a risky undertaking. Ships carrying this precious cargo were protected in the centre of convoy formations but some ships were torpedoed and sunk en route.
The City of Benares was a Canada-bound ship hit by German torpedoes that remains to this day the worst ever disaster involving British children. More than half those on board were lost, and out of ninety 'seavacuee' children escaping the bombing in Britain, seventy-seven died. After this tragedy, the efforts to evacuate children overseas was discontinued.