One day in late March 2010, Donald Ritchie stood in front of 57 Democratic senators gathered in the LBJ Room of the Capitol. It was the Democratic Conference's weekly lunch, and for years, Ritchie had been opening almost all of the group's meetings with a brief "Historical Minute"—a quick lesson on some aspect of Senate history.

(Peter Bull)Today's topic was the legendary Senator Bullwhip Randolph of Montana. "He was the first whip of the Democratic Party, and he actually carried a whip into the Democratic Conference," Ritchie explained. "It was the only time in the history of the Democratic Party that they all voted together on the issues. And after he left the Senate, he became a rodeo cowboy."

The senators, he recently recalled when I visited him in his office, "started out taking it seriously. But it was so over the top that, by the end, they all knew it was a tall tale." When he had concluded, they applauded, cheered, and laughed. "Was any of that true?" asked an incredulous Harry Reid, who was sitting next to Ritchie. "Not a word, Senator, not a word," responded the historian.

Ritchie, it turned out, had succumbed to the entreaties of freshman Sen. Al Franken, letting the former comic write this particular "Historical Minute," just before April Fool's Day. It was a rare moment when Ritchie, who retired last week, delivered information that was not meticulously accurate. The Senate Historian's Office was founded in 1975 by Richard Baker, who quickly hired Ritchie as associate historian. Over the next four decades, Ritchie (who took over the office when Baker retired in 2009) became famous for having all the answers. A former Marine who has written 12 books and three textbooks, he was the go-to guy for senators looking into historical precedents, for fellow historians like Robert Caro, for novelists like Dan Brown, for moviemakers who just had to know the color of hearing-room drapes, and for reporters like me.

He was the one I went to when Sen. Ted Stevens was indicted, in order to identify the first senator ever indicted (John Smith of Ohio in 1807). He was the one I went to when Bill Clinton was impeached, to find out how the Senate conducted Andrew Johnson's impeachment trial in 1868. He was the one who knew when the first female Senate page was named (1971) and when the first African-American was served in the Senate cafeteria (1953). He knew because he had done the research—personally spending hours, for example, talking to the black secretary who had first integrated the cafeteria or interviewing the one (now-deceased) person who knew every detail of the Johnson impeachment.

Last Friday, Ritchie, 69, packed up his office on the second floor of the Hart Senate Office Building. And on Tuesday, he boarded a plane for Milan, Italy, with his wife, Anne, who also retired on Friday from her job as archivist and oral historian for the National Gallery of Art. When we spoke in his office just hours before he left, Ritchie looked back on his tenure with satisfaction. There were the big accomplishments—the streamlined process for granting historians access to the papers of senators, the exhibits in the Capitol Visitor Center, the Senate Oral History Project. But he seemed to take more pleasure in the small, everyday achievements. "The most satisfying thing in general is when you provide some information and you hear somebody using it in a debate on the floor, in a speech," he told me.

One of the services that senators certainly appreciated were the "Historical Minute" lessons at caucus meetings. They were the idea of Sen. Tom Daschle, after his Democrats took a drubbing in the 1994 election. "He thought the caucus's spirits needed some picking up," Ritchie recalled, and so the senator asked Baker to open every lunch. "When he retired in 2009, so many senators made the point that the high point of their week was hearing those minutes," Ritchie said. So he continued them. (At the same time, Republican leader Mitch McConnell asked him to have a colleague deliver the "Historical Minute" at GOP caucus meetings as well.)

The short talks, Reid said in a recent floor speech about Ritchie's departure, are more than just informative. "It shuts up my caucus," he said bluntly. "Our lunches can be fairly boisterous, and they stop all conversations to listen to Don Ritchie."

For reporters, too, Ritchie was in demand—an aspect of the job that surprised him at first. He and Baker were creating the office as they went along and handling press queries was not in the original plan. "We never anticipated when we got started that we would essentially be providing information for the media," he said. But that became a major part of his role.

Never was that more true than during the Clinton impeachment. "That was the busiest," he recalled. "It was hard to get through to us on the phone. You were literally on the phone from the time you came in the morning, because there was a stack of voice mails that came in during the night. And by the time I had answered those questions, there were more questions. I had a red ear for the whole time."

Not all questions from reporters have been well-formed, of course. "I had someone wanting us to tell him where the campus of the Electoral College is located," he said. "Which, of course, required us to ... explain that it is not a university and they did not all meet together." Other requests have been trivial—the recipe for the Senate's famous bean soup, for instance.

Now, it will be someone else's turn to answer these questions. Ritchie seemed to relish the prospect of finally being free of his administrative and media duties; as he put it, "There won't be people like you saying, 'When was the last time this happened? When was the first time?'"Š" But he also made it abundantly clear that he enjoyed his run—and continued to believe strongly in the mission of the office he helped to create. "For a political historian," he told me, "this is the absolutely best place to be."

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