When members of the House and Senate file past the casket of Daniel Inouye as he lies in state in the Capitol Rotunda on Thursday, they will be mourning more than the death of a dear friend and historic colleague. They also will be grieving the passing of an era in which veterans of World War II dominated American politics.

In 1963, when Inouye joined the Senate, more than half of his colleagues shared an important bond with him: The distinguishing fact of their lives had been their service in that war. But, with Inouye’s passing this week at age 88, that era quietly comes close to its final moment. Inouye’s death and the retirement of his Hawaii colleague, Sen. Daniel Akaka, means the Congress that takes office in January will have only three World War II veterans—one in the Senate and two in the House.

The lone survivors are Democratic Sen. Frank Lautenberg of New Jersey, who turns 89 next month; Republican Rep. Ralph Hall, 89, of Texas; and 86-year-old Democratic Rep. John Dingell of Michigan. Lautenberg served in the Army Signal Corps from 1942 to 1946. Hall flew planes off aircraft carriers from 1942 to 1945. Dingell joined the Army when he turned 18 in 1944 and was in the invasion force poised to attack Japan when the war ended.

It would be difficult to overstate the influence of World War II veterans on governance through most of Inouye’s remarkable 53-year Capitol Hill career, during which Hawaiians elected him twice to the House and nine times to the Senate. Numbers compiled for National Journal Daily by the National World War II Museum in New Orleans show that 697 veterans of the war were elected to Congress. Some, including Inouye and former Sen. Bob Dole of Kansas, continued to wield power even half a century after the end of the war. But, for most, their greatest decades of influence were the 1960s and 1970s.

The Senate that Inouye entered when he moved over from the House was very much a veterans’ chamber. He was but one of 69 veterans in that Senate, according to the Senate Historian’s Office. A National Journal Daily analysis found that Inouye served with 25 senators who had fought decades earlier in World War I—and even with one, Arizona’s Carl Hayden, whose service began eight years before America entered that war. Another 39, including Inouye, had fought in World War II.

Ten years later, by 1972, the number of World War I veterans in the Senate had dropped to eight, while the ranks of World War II vets had grown to 55.

That war had an even stronger grip on Washington’s politics than had the Civil War in the previous century. Every presidential election from 1952 to 1996 featured a World War II veteran heading one of the two tickets—from Dwight Eisenhower to Dole, over 12 elections. Eight presidents, from Eisenhower to George H.W. Bush, were in uniform during the war. (Jimmy Carter’s was that of a midshipman at the Naval Academy.)

Few, of course, were as decorated for valor or left as much on the battlefield as Inouye did. As a member of an Army regiment of Japanese-Americans, he led a singular charge on three machine-gun nests in Italy in 1945, was struck repeatedly by enemy bullets, and lost his right arm to a hand grenade. For his bravery, he was awarded the Bronze Star, the Purple Heart, and the Distinguished Service Cross, which was later upgraded to the Medal of Honor.

But Inouye rarely talked about his war service or record. In that, he was typical of most of his fellows. Almost to a man, they believed that those days in combat put an emphasis on teamwork, not the individual. It was a philosophy that served Congress well for decades, but one much less apparent on today’s Capitol Hill. With the presence of veterans shrinking, even the highly respected Inouye, the second longest serving senator in history, was in danger of being viewed as an anachronism in an increasingly partisan chamber.

The Senate that opens next month will have the fewest veterans since the Senate Historian started tracking them in the 79th Congress, 1945-47. The number of veterans in the body peaked at 81 in 1977 and never fell below 50 until 1997. But as the veterans of World War II, Korea, and Vietnam age and retire, the decline has been rapid. The 113th Senate will include a record-low 18 veterans.

Veterans’ shrinking influence was also evident in the 2012 presidential race. The Barack Obama-Joe Biden and Mitt Romney-Paul Ryan tickets included no veterans, the first time that has happened since 1932.

Critics have also suggested that the vanishing number of veterans in politics has affected the way members approach issues and their willingness to work with others. Certainly, the mind-set is different from that of earlier generations, in which military service was either expected or—because of the draft—feared. No American born after 1952 has ever been subject to a military draft, and 30 of the 80 male members of the incoming Senate were born in 1953 or later. Combined with the 20 women in the Senate, that means fully half of the senators never had to worry about being drafted and were never exposed to the lessons of military cohesion, teamwork, and selflessness championed by Inouye, Dole, and other vets.

They are lessons that might be recalled as Inouye lies in the Rotunda on Thursday, resting upon the catafalque first constructed in 1865 for Abraham Lincoln. Inouye is the 31st person to be granted that honor, but only the seventh to be honored solely for his Senate service. Public viewing will be from noon to 8 p.m., with entry through the Capitol Visitor Center.

This article appeared in the Thursday, December 20, 2012 edition of National Journal Daily.