The advent of the US participation in the First World War signified a marked shift from the isolationist stance it had adopted by being neutral. Although a combination of factors—including trade alliances and the interception of the Zimmerman note—encouraged the decision to join the fray, Germany’s unrestricted submarine warfare was the biggest reason for the US involvement. Attacks on American ships constituted a direct assault on the sovereignty and territorial integrity of the US as a nation.
Attacks on American merchant ships by German U-boats posed a challenge to neutral position that the US had adopted when the war broke out. According to Knispel (2017), Germans knew that the US would be averse to unrestrained submarine warfare but launched it anyway as a provocation. There is a contention that German leadership had made an explicit admission on the day before the deployment of the submarines that they were counting upon war with America (Knispel, 2017).
Direct attacks on American vessels inevitably drew the US into the war since they constituted an affront to its sovereignty and territorial integrity as well as a blatant disregard to its declaration of neutrality. Although the Zimmerman Telegram was also influential, Knispel contends that there is no proof in any of the official records that the government took the threats contained in the note seriously (2017). Trade is also unlikely to suffice because the economies of its allies had already been devastated by the war and international commerce was not a priority at that point. Accordingly, sinking of the ships by the U-boats was the major reason for the US involvement.
Various factors were responsible for the involvement of the US in the First World War. However, the unrestricted submarine warfare employed by the Germans did not spare American merchant ships. Disregarding US’s neutrality and undermining its sovereignty and territorial integrity posed an open invitation to the war.
Reference
Knispel, S. (2017). Why did the U.S. enter World War I?. NewsCenter. Web.