That's the way they had been educated about submarine warfare, too.

"The nice thing about submarine warfare is that it takes place largely out of sight."

"It is truly the center of excellence in submarine warfare."

He studied submarine warfare from 1983 to 1984 for the chief of naval operations.

In 1916-17 he was an advocate of unrestricted submarine warfare.

The Cold War brought a new kind of conflict to submarine warfare.

On 18 September 1915, he called off unrestricted submarine warfare completely.

The new policy of unrestricted submarine warfare was initially a success.

In 1917 Germany decided to resume full unrestricted submarine warfare.

This reservation needs to be made in respect to the unrestricted submarine warfare only.