Final answer:
In September 1947, European nations signed up for the Marshall Plan and initially requested $29 billion in aid, establishing the Western alliance. President Truman later requested $17 billion from Congress, and about $12 billion was allocated from 1948 to 1951 to rebuild Western Europe and counteract communism.
Step-by-step explanation:
In September 1947, European nations signed up for the Marshall Plan and requested a total sum for aid, which signaled the strengthening of the Western alliance. The exact amount initially requested by these nations was $29 billion. However, this was promptly reduced by President Truman to $17 billion before he sought the necessary approval from Congress. While the final amount allocated over the duration of the plan was about $12 billion from 1948 to 1951 (approximately $147 billion in today's money), this aid was critical in helping Western Europe overcome the devastation of World War II. It facilitated the rebuilding of infrastructure, the revival of industrial capacities, and prevented the threat of communism from gaining a stronger foothold, particularly in France and Italy, by promoting capitalist democracies.