An old one, and said to be true...

On 7 December 1941 a British corvette was in the North Atlantic leading the escort of a large UK bound convoy. The convoy had already been attacked by German submarines and several ships sunk. The ships of the convoy had become somewhat scattered and communications with them in the prevailing gale and heavy seas were very difficult. The corvette itself had been damaged and was unable to use its weapons. The Captain had broken his leg and was turned in down below.

On the bridge the second-in-command faced a bleak prospect. He knew that another submarine pack was between him and the convoy's UK destination. The weather was improving but a further severe gale with low visibility was forecast.

In the radio office a Secret, Most Immediate, signal was received. It was laboriously decoded and passed urgently to the bridge. The second-in-command read:

"Commence hostilities against Japan."