Lusitania would have been a legitimate target if she was commissioned as an armed merchant cruiser. This is why the suggestion was made by the Germans that she had been so armed while in New York. Many of the faster liners were used, as indeed were liners used as commerce raiders by Germany.

In the event the larger liners weren't used as AMCs because they were too expensive to run with their large crews and vast coal consumption.

The warnings issued by Germany about the Lusitania and the information from German agents prove that the Germans knew that Lusitania was in service as a passenger liner. The uproar that this sinking caused was similar to that caused by the shelling of English towns by battlecruisers and the bombing by Zeppelins, that the Germans were indiscriminately targeting civilians.