'Hornblower' was the British second stage of the preparations for the demolition of the harbour of Alexandria on Egypt’s Mediterranean coast in the event that the Axis ground forces appeared likely to advance that far in 'Aïda' (29 June 1942).

The depth charges and other explosives which would be required for the implementation of the scheme were readied but not moved into position for fear of alerting anti-British Egyptian elements which might then relay the information to the Axis forces.