[SeeSharp]

The Lusitania was carrying war materiel, but it certainly had no capability to take offensive action against submarines.

International law prior to the war required submarines to surface and offer unarmed ships the opportunity to surrender rather than just sinking them without warning. Churchill publicly ordered all British ships to ram any German submarine on the surface demanding surrender.

[buccaneer81]

Right, but submarine warfare brought an end to those rules as subs were considered highly vulnerable if they surfaced.

One story, which may or may not be true contends that the Quartermaster of the U-20, when given the order to fire by the CO, refused to do so, citing the presence of women and children aboard the Lusitania. He was court-martialed and spent three years in a military prison.