Read the passage.

As Chief of Staff of the U.S. Army before and during World War II, [George C.] Marshall earned a great share of the responsibility for the Allied victory. He helped plan, train and deploy ten million American soldiers and airmen, managing also the scientific development and procurement of the ever-increasingly complex weapons.

After a few days of retirement following World War II, Marshall was called upon by the President to help manage the crucial problems of waging peace. As Secretary of State from 1947 to 1949, he was the personal architect of the American diplomatic and economic program which turned the tide of Communism in war-ravaged Western Europe. This program came everywhere to be known as the "Marshall Plan" and led to the coalition of free nations under the North Atlantic Treaty Organization (NATO), paving the way for a revitalized Europe. For this, Marshall received the Nobel Peace Prize in 1953.

–“Biographical Sketch of George C. Marshall,”
Marshall Space Flight Center

According to the passage, what were George C. Marshall’s military contributions during World War II? Check all that apply.
1. He served as chief of staff of the US Army.
2. He helped train US soldiers and airmen in modern warfare.
3. He used and helped advance modern weaponry.
4. He led British and French Allied forces as well as US forces.
5. He reduced the size of the US military from millions of troops to thousands.