Margaret L. “Maggie” Wimsatt, a planner and organizer of high-profile social events for the rich, the powerful, the well-connected and the well-known of the nation’s capital, died of cardiac arrest March 13 at Shady Grove Adventist Hospital in Rockville. She was 95.

A daughter, Justine Wimsatt, confirmed her death.

Mrs. Wimsatt was widely recognized as a maven of protocol who knew which closets harbored skeletons and which didn’t. She once saved the day with a last-minute switch in seating arrangements for a dinner party hostess who had unknowingly placed the guest of honor at the same table with his ex-wife and his ex-girlfriend, according to a 1982 article in Washington Dossier magazine.

“That could’ve been a disaster,” Mrs. Wimsatt told the magazine. “I seated them on opposite sides of the room.”

For more than six decades in Washington, Mrs. Wimsatt served on a plethora of boards and committees of charitable and civic organizations. She held public relations and fundraising positions and was an editor of Washingtonian magazine’s Benefits column.

Margaret L. Wimsatt, left, prepares her weekly shopping list with the help of her daughter, Tina, at their house in Washington, D.C. on March 28, 1957. (Henry Rohland/The Washington Post)

She arranged debutante parties, weddings, fundraising dinners, charity balls and embassy receptions during an era when Washington was governed by a greater sense of gentility and manners.

“It was unthinkable,” a Washingtonian story noted in 2008, “to schedule a major event without calling Maggie first.”

Margaret Louise Sampson was born Jan. 27, 1918, in St. Louis and lived in the Washington area intermittently in her youth. Her father was an Army colonel.

She attended Western High School for two years and graduated from Glen Burnie High School in 1935. Her grandmother disapproved of the way she spoke, so Mrs. Wimsatt studied diction, drama and arts at the King-Smith Studio School in Washington for two years.

As a young woman, Mrs. Wimsatt attended Christmas balls at the White House and rode horseback in Rock Creek Park and at Fort Myer. At that time, high-ranking military officers were expected to present their calling cards to the president and the secretary of war.

“My mother had a Buick touring car,” Mrs. Wimsatt told Washingtonian. “She and my grandmother, my sister and I drove up to the guard at the White House and said, ‘We are leaving cards.’ We drove right up to the front door. A man in livery came out with a silver tray. My grandmother put my mother’s and father’s calling cards on the tray, and then we drove away.”

In 1939, she married James McSherry Wimsatt, a fourth-generation Washingtonian whose family operated a lumber business. During World War II, he ran family farms in Virginia. Mrs. Wimsatt lived in Chevy Chase from 1945 to 2008, when she moved to Rockville.

From 1964 to 1971, she was a consultant and coordinator of special events in the office of the director of the National Park Service. In 1976, she was director of protocol and seating for a program with 2,300 attendees at the Kennedy Center.

In the course of her career, Mrs. Wimsatt planned special events at hotels in Washington, consulted on public relations with the Woodward & Lothrop department stores, and served on the boards of the National Symphony Orchestra, International Eye Foundation, American Heart Association and Georgetown University Hospital, among others. She organized benefit dances and other events for Georgetown Hospital and was on the executive committee of the annual gala for Georgetown’s Lombardi Cancer Center. She had been a member of the Sulgrave Club since 1948.

Her husband died in 2004 after 65 years of marriage. Survivors include three children, James McSherry Wimsatt Jr. of Stevensville, Md., Catherine W. Mecklenburg of Auke Bay, Alaska, and Justine S. Wimsatt of Burtonsville; and three grandchildren.

In the interview with Washingtonian, Mrs. Wimsatt recalled going to a wartime party at the home of Evalyn Walsh McLean, the mining heiress and socialite.

“A young man was talking to Mrs. McLean and he asked her about the jewelry she was wearing,” Mrs. Wimsatt said. “She handed him one piece and said, ‘Here — this is the Hope Diamond.’ I’ve never forgotten the look on that kid’s face. After that we passed it around.”