The nation and the world are mourning the loss of former First Lady Nancy Reagan, who died Sunday in California at the age of 94.

She will be remembered most as the backstage adviser and fierce protector of Ronald Reagan. She was firmly by his side from his days as an actor, then as governor and president and during his 10-year battle with Alzheimer's.

As first lady, she made an impact on the public wherever she went.

University of Denver Associate Professor Jing Sun said Nancy Reagan paved the way for more meaningful roles for international leaders' spouses. He saw how she shaped American diplomacy through kind gestures and sincerity during a historic trip to China.

As an 11-year-old in Beijing, Sun watched as President Reagan and the First Lady visited China in 1984.

"I was actually left speechless," he said.

Sun said he saw Nancy Reagan single-handedly change the American image in the eyes of the Chinese public.

"I just remember this lady dressed in red doing a number of things that usually, it just never occurred to me that a First Lady could actually hug someone," he said.

Sun described her elegance, charm and sincerity as holding nearly as much political power as America's military and economy, and that "soft power" spread globally.

"Nancy Reagan is a household name not just in America but on the international stage as well," he said.

Sun credits President Reagan's wife for setting the foundation for what First Ladies could do for the county's image, even after the powerful couple left the White House.

When Ronald Reagan was diagnosed with Alzheimer's Disease in 1994 and died a decade later, she became a spokesperson for her husband's ideas and legacy.

"I think what she did could offer valuable lessons to all the future first ladies," Sun said.

Sun said because of the trip to China in 1984, Nancy Reagan is nearly as famous as President Reagan to this day. He said Chinese First Ladies learned from her how to play an important role in politics.