This is the official Naval Staff history of the Norway campaign, originally published internally in 1951. It covers the period from early April 1940 to the completion of operations in June. The operation involved most of the Royal Navy's ships in the Home theatre at the time.

This volume deals with the first 15 months of the Mediterranean Campaign including the preparations for war, the effect of the entry of Italy into the war in June, 1940, the tragic actions against the French Fleet, and the achievement of British command of the sea, which was the defining factor for all subsequent Mediterranean operations. It ends with the first Mediterranean convoy battle to run supplies from Gibraltar to Alexandria - Operation Hat.