Henry Agard Wallace was the 33rd vice president of the United States (1941–45) in the Democratic administration of Franklin D. Roosevelt. He was also the Secretary of Commerce under the Truman administration after he was Vice President under Franklin Delano Roosevelt.
The letter you are referring to was written by Henry Wallace on July 23, 1946. The letter was addressed to President Harry S. Truman. The letter was written after Wallace was asked to resign by Truman.