Nancy Reagan touches the casket of her husband, former US President Ronald Reagan, as it lies in state in the rotunda of the United States Capitol in Washington in this June 9, 2004 file photo. [Photo/Agencies]

As Reagan's wife, political partner and adviser, she became one of America's most potent first ladies, alongside the likes of Franklin Roosevelt's wife, Eleanor, Woodrow Wilson's wife, Edith, and Bill Clinton's wife, Hillary.

"I see the first lady as another means to keep a president from becoming isolated," she said in 1985. "I talk to people. They tell me things. And if something is about to become a problem, I'm not above calling a staff person and asking about it. I'm a woman who loves her husband and I make no apologies for looking out for his personal and political welfare."

Tiny and frail in her later years, Reagan devoted her time to caring for her ailing husband at their home in Los Angeles' exclusive Bel Air enclave. She was always a stickler for protocol and detail and stoically presided over the former president's weeklong funeral and celebration of his life in June 2004.