President Trump warned about investigations of his administration as he gave his State of the Union address this month. (Doug Mills/Pool photo via New York Times/AP)
Nancy Beck Young is professor of history at the University of Houston and author of multiple books including "Why We Fight: Congress and the Politics of World War II" and the forthcoming "Two Suns of the Southwest: Lyndon Johnson, Barry Goldwater, and the 1964 Battle between Liberalism and Conservatism."

In last week’s State of the Union address, President Trump presented Americans with a set of binaries. “If there is going to be peace and legislation, there cannot be war and investigation,” he claimed. “It just doesn’t work that way.”

Well, actually, it does. Trump may have been referring to war with Congress. But in reality, the United States has long managed to prosecute actual wars, legislate and have congressional oversight and investigations simultaneously. War, investigation and legislation can and do go hand in hand, but only when there is competence in all branches of the government (which might be why Trump finds the combination so baffling).

Wartime lawmakers in the 1940s investigated myriad things, some serious and some inane. The most serious inquiries came from what was commonly known as the Truman Committee, formed in 1941. Then-Sen. Harry S. Truman (D-Mo.) chaired the panel, which was tasked with ferreting out waste in the defense industry. Formally known as the Senate Special Committee to Investigate the National Defense Program, the Truman Committee proved invaluable to the success of the war.

Oversight was crucial because of the amount of money being spent. In 1940, well before the U.S. had joined World War II, Congress had already appropriated $10 billion for national defense. Early the following year, still months before Pearl Harbor, Truman heard rumors that contracts were being mismanaged. His response was to take a 10,000-mile tour of U.S. military bases to investigate the conditions for himself.

Truman learned two things: first, that contractors earned a fixed profit regardless of the efficiency with which they did their work and, second, that contractors located on the East Coast procured a disproportionate number of the contracts.

He called for a special Senate committee to undertake an in-depth investigation. Top military officers were opposed, fearing a repeat of the Civil War experience with the congressional Joint Committee on the Conduct of the War, which examined why the Union lost key battles and pushed President Abraham Lincoln to take a more aggressive posture against the Southern rebels. But lawmakers convinced President Franklin D. Roosevelt that an investigation was unavoidable. They also explained that Truman, who supported the war effort, was a good choice to head it. They noted his budget for this bipartisan inquiry would be minimal, at only $15,000.

This fiscal restraint did not slow Truman. He made himself into the “bogeyman to all national defense chiselers” with his thorough study of national defense spending. Later, in April 1943, Truman explained to an interviewer his philosophy for pursuing this work: “war is waste — waste of manpower and material.”

Truman chaired this special committee for three years. He earned a favorable national reputation while also saving the country millions of dollars. This work was no small factor in his selection in 1944 as Roosevelt’s running mate.

Not every wartime investigative committee proved so benign. Another example of wartime investigation ranged from inane to dangerous: the House Special Committee to Investigate Un-American Activities, under the chairmanship of Rep. Martin Dies Jr. (D-Tex.).

Dies and Truman could not have been more different by World War II. While both had been ardent New Dealers in the early 1930s, Dies grew skeptical of the reform initiatives, especially when labor unions gained protection and when discussion turned to civil rights.

Dies’s nickname, given to him by his friends, was “der Fuehrer,” the same title applied to Adolf Hitler. The title appears in a letter from another member of the Dies Committee to the committee staff, in which he affectionately referenced Dies by the nickname. Moreover, at least one witness who testified before the Dies Committee greeted Dies with the “Heil Hitler” salute.

While the congressional intent of the Dies Committee had been to reveal and help eliminate fascist threats in the United States, Dies preferred to investigate communist threats. He did so because he believed this line of assault would bring down Roosevelt and the New Deal, his real targets.

House leaders knew Dies liked to operate “with a bazooka in one hand” and “a fireball in the other,” but they still gave him this committee assignment, thinking he could be contained and would not damage the war effort. His committee’s budget was much higher than Truman’s, at $100,000.

Dies introduced many of the rhetorical devices that Sen. Joseph McCarthy (R-Wis.) used to great consequence in the postwar years, including “I have here in my hand” (as he waved papers aloft), references to “reliable evidence” that he could not “disclose at the present time,” and attacks on liberal Democrats for “coddling” Communists.

At the end of the day, though, Dies’s disruptive behavior had no lasting impact on the war effort or the stability of democracy during the 1940s. It created dangerous tropes and tactics that would do damage to American society in the years to come, but it did not destroy the Roosevelt presidency or the administration’s legislative agenda.

What this reveals is that investigation and congressional oversight provide needed sunshine and, even in their worst incarnation, do not interfere with the executive branch’s ability to function and even to prosecute a war. Sunshine has always been and will always be the best disinfectant against governmental corruption and overreach.

As long as any investigations of the Trump administration undertaken by Democratic-controlled House committees are pursued with the same integrity as that of the Truman Committee, while avoiding the demagoguery of the Dies Committee, the Trump administration will still be able to function and even collaborate with Congress to better the lives of average Americans. To do so, however, it will need to bring the same level of competence to governing that the Roosevelt administration deployed in the 1930s and 1940s.