(CNN)More than 50 years after he was nearly beaten to death marching for civil rights in Alabama, Rep. John Lewis is again at the front lines of a pitched battle over America's future.
Who is John Lewis?
The congressman from Georgia is making headlines and stirring up what he likes to call "good trouble" for his vocal opposition to President-elect Donald Trump. Lewis will boycott Trump's inauguration on Friday and told NBC News last week, "I don't see this President-elect as a legitimate president."
The long-serving Democrat was a young activist and leader of the Student Nonviolent Coordinating Committee when, in March 1965, he joined forces with Martin Luther King Jr. to lead a voting rights march out out Selma, Alabama.
But as the nonviolent demonstrators approached the Edmund Pettus Bridge, on their way to the state capital in Montgomery, they were confronted by heavily armed state troopers and local police. When the march refused to turn back, protesters were set upon and beaten.
The images from "Bloody Sunday" -- and Lewis, who was photographed under assault and suffered a fractured skull -- helped galvanize support for the Voting Rights Act, which was signed into law by President Lyndon B. Johnson months later, on August 6.
In a series of tweets on Monday, as Americans observe a federal holiday in honor of King, Lewis recalled the man he often describes as a "big brother."
"Dr. King taught us to recognize the dignity and worth of every human being. He was the moral compass of our nation," he tweeted.
King "marched for us," "protested for us," "went to jail for us," and ultimately "gave his life for us," Lewis wrote.
Born in Troy, Alabama, on February 21, 1940, Lewis attended segregated schools and began organizing in his teens, helping coordinate student sit-in demonstrations in Nashville in 1959 and 1960.
By 1963, he was the chairman of SNCC, a post he would hold through a dangerous era that saw civil rights leaders targeted and assassinated, but also the passage of the Civil Rights Act. In August 1963, the 23-year-old delivered a keynote address at the March on Washington.
After being appointed to lead the federal volunteer agency, ACTION, by President Jimmy Carter in 1977, Lewis was elected to the Atlanta City Council in 1981. Five years later, he won his first congressional race. He has served now for decades as the US representative from the Georgia's Fifth District.
In February 2011, President Barack Obama presented Lewis with the Presidential Medal of Freedom, the country's highest civilian honor.