As chair of the House Armed Services Committee, Rivers developed a reputation for his unwavering support of American involvement in the Vietnam War.

The law school dean at the University of South Carolina advised Rivers to take up another profession because, although he knew the assignments, he suffered from stage fright.

[citation needed] Rivers was determined to become a lawyer so he returned to College of Charleston, took classes to prepare himself for the bar examination.

[citation needed] After passing the bar exam in 1932, he was unable to find work in Charleston law firms during the Great Depression, so he started his own practice.

Rivers first became involved in politics in 1930 when he participated in Ed Pritchard's unsuccessful campaign for the state legislature against Russell McGowan.

A vacancy on the Charleston County delegation arose in 1933 when Ben Scott Whaley resigned to join the staff of Senator James Francis Byrnes.

Rivers won the special election by running against Charleston and campaigning on the slogan "Give the Northern End of the County Representation.

McMillan arranged a meeting with Rivers and offered him a position as a Special Assistant to the Attorney General of the United States.

His opponent in the Democratic primary was Alfred von Kolnitz, who had the backing of the Charleston political establishment and Thomas McMillan's widow, Clara.

Furthermore, with World War II raging in Europe, Rivers played up von Kolnitz's German name to make him appear as if a Nazi sympathizer.

In those days, victory in the Democratic primary was tantamount to election in South Carolina, and Rivers took office on January 3, 1941.

His first legislative success was in 1942 when he authored a bill to build an oil pipeline from Mississippi to the Southeast coast to reduce the transportation costs of the product.

The bill was passed by Congress and signed by President Roosevelt, but Secretary of the Interior Harold L. Ickes refused to construct the pipeline because of the opposition by Big Oil.

[15] Rivers attempted to have Charleston federal district court judge J. Waties Waring impeached for having ruled that blacks had to be allowed to vote in the Democratic primary and that segregated schools were unconstitutional.

Judge Waring was buried in Magnolia Cemetery on Meeting Street in Charleston and his funeral was attended by more than 200 blacks and less than a dozen whites.

However, Rivers became disillusioned with Stevenson and he openly supported Republican Dwight D. Eisenhower in the 1952 Presidential election because he said that he would be sensitive to Southern concerns.

Upon moving into the Rayburn House Office Building, Rivers placed a plaque of Article 1, Section 8 of the United States Constitution that specified the role of the legislative process with the military.

[24] As Rivers inspected the committee room, he became incensed when he discovered there were cloakrooms adjoining the chamber for use by Democratic and Republican Party members to discuss their strategies.

After becoming chairman, in 1965 he helped secure the first military pay raise since 1952, despite opposition from the Secretary of Defense McNamara and President Johnson.

Rivers was instrumental in establishing the additional enlisted pay grade of E-9, and he helped secure mobile home allowances and cheap air fares for soldiers returning from Vietnam.

He supported making all US Navy ships nuclear powered,[26] and he championed development of the US Air Force's C-5A Galaxy military airlift jet, despite huge cost overruns.

[27] In his last speech to his colleagues in the US House of Representatives on December 7, 1970, delivered just before he departed for Birmingham, Alabama to have heart surgery, he stated, "While we debate the question of maintaining our military capability, the Soviet Union forges ahead.

"[31] During a Congressional investigation of the 1968 Mỹ Lai Massacre, Rivers criticized Army helicopter pilot CW2 (later Major) Hugh Thompson, Jr. for giving the order to his men to fire upon American soldiers at Mỹ Lai if they continued to shoot unarmed Vietnamese civilians, calling him a traitor and saying he should be prosecuted.