From the very first days of WWII, Germany
and the Allies fought at sea. The control
of the ocean routes that carried all kinds
of supplies to Great Britain soon became
one of the war's key issues: for six years,
a desperate battle is fought in the Atlantic,
as Allied navies try to protect merchant
ships against Germany's formidable U-boats.
When France falls, Great Britain calls upon
Canada; the Royal Canadian Navy undertakes
a dramatic effort to increase its strength
and efficiency. Within six years, it will
become one of the world's most powerful
navies.