In January 1916, Arthur Zimmermann, foreign secretary of Germany, send a coded telegram to German’s ambassador to Mexico. This telegraph was intercepted by British agents and decoded, exposing its contents. Within the telegraph Zimmermann wrote to their ambassador to Mexico, that if America looked to join the war, they (Germany) should approach the Mexican government and offer support and reward their support in return for Mexico’s allegiance in the war. This telegraph was exposed to the American public in March, leading to widespread anger, and thus contributed to the declaration of war in April.
Had the telegraph not been intercepted, or had the attempts to decode it failed, there was plenty of other causes that justified America’s entrance into the war. Furthermore, Mexico had analyzed Germany’s proposition and concluded that war with America wouldn’t achieve their goals of recapturing lost territories, nor would it be beneficial.
I agree that this played an important role for America to enter into World War I. The Americans initially didn’t want to join the war in fear of endanger the country for unreasonable casualties. America at the time were only helping the alliance through making war supplies and that’s it. After seeing that their own country is being threatened by Germany, America had no choice but to enter into this war. This news of possible danger alarmed and angered Americans and ultimately changed everybodies mind on entering the war.
Although this letter did not influence Mexico to enter the war on the side of the German’s, this letter became a huge deciding factor to Germany’s its alliance’s fate in this war.