By Adam Desiderio, NBC News

Invoking the spirit and struggles of the civil rights movement, Myrlie Evers-Williams, the widow of slain civil rights leader Medgar Evers, delivered the invocation for President Barack Obama’s second inauguration Monday, addressing the hundreds of thousands of visitors that had descended upon the National Mall.   

Evers-Williams is the first woman -- and the first layperson -- to give a presidential invocation. This year’s inauguration comes 50 years after her husband Medgar Evers, an NAACP Mississippi field secretary, was shot and killed in the driveway of their home. It also happens to fall on Martin Luther King Jr. Day, marking two important anniversaries in the fight for civil rights. 

“I'm so honored to be asked to do this and it's so important that it comes at a time when the nation will look at Medgar and others who died doing that that 50-year period, it's just critically important,” Evers-Williams told "NBC Nightly News." 

Evers-Williams was a 30-year-old wife and the mother of three young children when men came to her house in Jackson, Miss., on June 12, 1963, and shot her husband just steps from the front door.  

It was after midnight, the same evening President John F. Kennedy had delivered a landmark speech on civil rights to the nation. Medgar had called his wife earlier that day and asked her to let their children stay up to watch the president speak. 

“The children heard the sound of the Medgar’s car arrive in the driveway,” she recalled. “He drove the car into the driveway and there was the most horrendous sound of gunfire.  There was no question what had happened.” 

'I have never seen so much blood'

Medgar was shot in the back. He had the keys to his house in his hand.  

“I just remember the screams, I remember my children pleading for their daddy to get up, and I remember the blood. I have never seen so much blood,” she said.   

Though Evers-Williams was filled with anger and unspeakable grief in the wake of the murder, she found solace by continuing her late husband’s activism and championing the fight to end racial violence.  After a drawn-out period of three decades and two hung juries, white supremacist Byron De La Beckwith was convicted of murder on Feb. 5, 1994.

“I promise you, every pore of my body was open and it was just like ghosts were streaming out,” Evers-Williams said.  “When you remove yourself from the anger and the bitterness and you focus on the positive, and you search for the meaning for the anger and the hatred that took this man’s life, you either sink to that level or you rise above it all.” 

The struggle to achieve

One of the ways Evers-Williams continued in her late husband’s footsteps was by becoming chairman of the National Board of Directors of the NAACP in 1995, a position she held for three years.

“It was a slow process,” Evers-Williams said. “I struggled with being successful and achieving things as my way as payback, and it took a different turn, it was to achieve and to do and to help other out of love, not out of hatred.”

Today, on the steps of the U.S. Capitol, Evers-Williams remembered her husband and other civil right leaders that came before her.

“Approximately four miles from where we are assembled, the hallowed remains on men and woman rest in Arlington Cemetery," she said. "They who believed, fought, and died for this country. May their spirit infuse our being to work together with respect, enabling us to continue to build this Nation.”

She ended her invocation with the chorus from “Something Within,” a hymn by composer Lucie E. Campbell.

“There's something within me that holds the reins. There's something within me that banishes pain. There's something within me I cannot explain. But all I know, America, there is something within.”