Invasion: Oceania!

From publisher blurb: The year is 1941 and the Nazi menace looms across Europe. Britain stands defiant but has been pushed to her limits. Without the support of her allies in Canada, America and Oceania, Hitler is convinced Britain will finally be brought to her knees. However, even Hitler's mighty U-Boat fleet cannot stand against the undersea kingdom of Oceania, staunch ally of Britain through WWI and now WWII. Hitler has decided the first step to control of the Atlantic must be- Invasion: Oceania! The noose is tightening ever more around stalwart Britain. Only by coming to Oceania's aid can she be saved. Who will descend into the depths to defend Oceania?