No, Rooster I don't think it was. The Germans had declared the seas around the UK a war zone (which was not their prerogative to do) and fired upon what they had to know was not a military vessel, drowning 1200 innocents, and stoked the world fury against them. After the sinking, Germany 'promised' not to target passenger liners again, I think an admission of guilt. Nonetheless, it was done. The hideous war that followed essentially emasculated the entire German society for the next two decades, and fertilized the landscape for the rise of Hitler. I give the analogy that the Germans were "piled on" by the allies because of the Lusitania (especially in the Versailles Treaty) in the same way Japan was double nuked because of Pearl Harbor. It was a really bad move, IMO.
No it wasn't and I agree with my friend Z on this. Bad tactical move made by a group of people who single handedly changed the course of history to their future demise.