He was chief of the Armed Forces Special Weapons Project from 1952 to 1953, and Chairman of the Military Liaison Committee of the United States Atomic Energy Commission from 1954 to 1961.

A graduate of the United States Military Academy at West Point, he was commissioned in the US Army Corps of Engineers in 1919.

The next year he was appointed as an Army member of the Military Liaison Committee of the United States Atomic Energy Commission.

He was Deputy Commander of Joint Task Force 3, which was responsible for the conduct the Operation Greenhouse nuclear tests in the Pacific.

[3] Loper was appointed to the United States Military Academy at West Point from Nebraska and entered on 14 June 1917.

He was stationed at Camp Travis, Texas until June 1920, when he commenced studies at the Massachusetts Institute of Technology, from which he graduated in August 1921,[5] with a Bachelor of Science degree in engineering.

He returned to the United States in December 1926 and was with the Engineer Reproduction Plant at the Army War College until 31 August 1929.

[7] Loper attended the United States Army Command and General Staff College at Fort Leavenworth, Kansas from August 1939 to February 1940.

[10] Later Loper, who was promoted to brigadier general on 11 November 1944,[3] was involved in gathering engineer intelligence for the Battle of Iwo Jima, the Okinawa campaign, and Operation Olympic.

After the fighting ended, Loper became Deputy Engineer of United States Far East Command during the Occupation of Japan.

[6] On 1 November 1949, he was appointed as an Army member of the Military Liaison Committee of the United States Atomic Energy Commission (AEC).

The Loper Memorandum, as it became known, was influential in persuading the Joint Chiefs, the Secretary of Defense, and ultimately the President to authorize a crash program to develop thermonuclear weapons.

[14] In 1951, Loper was Deputy Commander of Joint Task Force 3, which was responsible for the conduct the Operation Greenhouse nuclear tests in the Pacific.