Why are the sinking of the Lusitania and the Zimmerman telegram significant?
1 Answer
Probably because they triggered the intervention of the US in the war.
Explanation:
The sinking of the Lusitania (with the loss of civilian American lives) produced a huge resentment in the public opinion against unrestricted submarine warfare launched by the German Navy. Probably the Lusitania (like other "neutral" freighters) was also carrying ammunition to England because there are suspects that its sinking was quite immediate and destructive after the torpedoing but anyway this was an open act of aggression against a clearly marked non-belligerant vessel.
Even worse was the Zimmerman telegram instigating the Mexican government to declare war on the US promising (in case of victory) huge extensions of American territory (Texas, Arizona and New Mexico, if I remember correctly). The "secret" telegram of the exterior minister Zimmerman was intercepted by the British and promptly disclosed to the US autorities...if there were any doubt about intervention this episode certainly settled it down against Germany.
