American Secretary of State Dean Acheson once said that the U.S. Congress was “an unhappy, unnecessary, unconstructive evil which you have for the purpose of getting money and passing some legislation”. This article will argue that Acheson was mistaken: the Congress and the American military proved constructive, necessary forces in the drafting of the North Atlantic Treaty (NAT) and America’s Cold War alliance strategy. The article attempts to make four contributions to the scholarly literature. First, it provides the first ever comprehensive look at the significant role the Congress (primarily the Senate) and the military played in US decisions on the NAT and alliance commitments in the early Cold War. Second, the article argues that the Congress and the U.S. military improved American alliance strategy. Third, it shows how the initial battles between the Senate and the White House on the North Atlantic Treaty and the “great debate” provided the template for subsequent American alliance commitments: the US would make commitments that were very limited in formal, legal terms but would provide de facto commitments (i.e., large contingents of ground troops) to those states that it deemed critical for American national security. Finally, the article contributes to the growing literature that has begun to chip away at the conventional view of a rational, executive dominated early Cold War foreign and security policy.